JP2007291492A - Composite material, its production method and ornament - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pink composite material having excellent corrosion resistance and aesthetic properties, and to provide an ornament. <P>SOLUTION: The composite material comprises one or more first phases essentially consisting of Pt and one or more second phases comprising Cu, and in which the content of Pt is 40 to 75 wt.% in the whole composition. Alternatively, the composite material further comprises a third phase, in a space between the first phase and the second phase, contacted with both the phases, and containing an intermetallic compound formed of Pt and Cu, and the maximal value of the reflectivity of natural light in the surface lies in the range of 560 to 640 nm in wavelength. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a composite material containing Pt and Cu, a method for producing the same, and a decorative article using at least a part of the composite material.

  Conventionally, as a Pt alloy, a Pt—Pd alloy, a Pt—Pd—Cu alloy, a Pt—Pd—Ru alloy, a Pt—Pd—Co alloy, a Pt—Ru alloy, a Pt—Co alloy, a Pt—Ir alloy, etc. is there. These Pt alloys exhibit a white color that matches well with gemstones. On the other hand, Pt shows a considerably lower reflectance than silver (Ag), its neat shine, its price is higher than gold (Au), and rareness is also recognized. Rarely used for jewelry.

  Due to the diversification of tastes in recent years, there is a demand for multicolored Pt as well as gold ornaments and silver ornaments. For example, pink is attracting a lot of support from women, as can be seen in silver ornaments, and pink is expected to appear as an ornament for Pt. However, in order to give pink color to Pt, there is a restriction that 80% by weight or more of copper must be added in the case of the casting method. Thus, when many base metals are added in order to give color to Pt, corrosion resistance will fall remarkably.

  As a pink metal material containing Pt, there is a mixture of In—Pd and an intermetallic compound of a Pt—In alloy (see, for example, Patent Document 1).

In addition, attempts have been made to develop various colors by adding Cu to an intermetallic compound PtAl ₂ of Pt and aluminum (Al) or by melting Pt.Al.Cu together (for example, patents). Reference 2). More specifically, in Patent Document 2, a yellow compound is obtained by setting the addition amount of Cu to 1 to 8% by weight, and a brown compound is added by setting the addition amount of Cu to 8 to 15% by weight. It is described that reddish brown (pinkish-brown color) can be obtained by adding 20 to 30% by weight.
JP 2000-226625 A JP-A-3-158430

  However, with respect to Patent Document 1, the content of Pt for generating a pink color is 12% by weight, and if the Pt content is increased beyond this, it becomes gray or yellow, and a good pink color development. I can't hope. When the Pt alloy is used as a jewelry, if the content exceeds 50% by weight, pink color development cannot be expected. On the other hand, the corrosion resistance is expected to be remarkably deteriorated by containing a large amount of a base metal element, and cannot be said to be a jewelry material having corrosion resistance that can withstand practical use.

On the other hand, since the metal material described in Patent Document 2 is formed by adding Cu to the intermetallic compound PtAl ₂ of Pt and Al or by melting Pt · Al · Cu together, Is considered to be an intermetallic compound. Such an intermetallic compound has a tendency that the reflectance increases monotonously as the wavelength increases in the visible light range in the wavelength dependency of the reflectance. For this reason, there is a problem that a desired color is not obtained because a color having a plurality of wavelengths is mixed.

  An object of the present invention is to provide a pink composite material and a decorative article excellent in corrosion resistance and aesthetics.

  In the first aspect of the present invention, one or a plurality of first phases mainly composed of Pt and one or a plurality of second phases containing Cu are provided, and the reflectance of natural light on the surface is There is provided a composite material characterized in that the maximum value has a maximum value of reflectance in the range of a wavelength of 560 nm to 640 nm.

  It is preferable that the reflectance of natural light on the surface of the composite material monotonously decreases, for example, in a wavelength range of 640 nm to 740 nm, and has a minimum reflectance in a wavelength range of 460 nm to 560 nm.

  Preferably, the content of Pt is 40% by weight or more and 75% by weight or less in the total composition.

  The plurality of second phases are arranged, for example, in the first phase, or the plurality of first phases are arranged, for example, in the second phase.

  According to a second aspect of the present invention, there is provided a method for producing a composite material according to the first aspect of the present invention, in which a metal particle containing Pt and a metal particle containing Cu are mixed to form a molded body. And the manufacturing method of a composite material characterized by performing the discharge plasma sintering of the said molded object in a vacuum atmosphere is provided.

  The firing temperature is, for example, 200 ° C. or more and 500 ° C. or less. The molding pressure when forming the molded body is, for example, 100 MPa or more and 550 MPa or less.

  A third aspect of the present invention is a decorative article having a composite material region formed of a composite material, wherein the composite material is according to the first aspect of the present invention, Decorations are provided.

  According to the present invention, by setting the maximum value of the reflectance of natural light on the surface in the range of 560 nm or more and 640 nm or less, the reflectance at the red wavelength becomes a peak, and the influence of mixing with the wavelength of other colors is small. As a result, only the desired pink color can be emphasized. As a result, the composite material of the present invention becomes a pink composite material with excellent aesthetics. In addition, by having the first phase containing Pt as the main component and the second phase containing Cu, even if the polishing progresses somewhat, it exhibits a metallic luster colored in pink.

  In the present invention, if the reflectance of natural light on the surface monotonously decreases from a wavelength of 640 nm to 740 nm and has a minimum value of the reflectance in the wavelength range of 460 nm to 560 nm, the influence of the wavelength of another color is affected. Since it can be suppressed appropriately, a more desirable pink coloring is exhibited.

  In the present invention, if the Pt content is 40% by weight or more and 75% by weight or less, the Pt ratio can be improved because the ratio of Pt is relatively high, so that it exhibits the original metallic luster of Pt and is resistant to corrosion. It will be excellent.

  If the composite material according to the present invention further has a third phase in contact with the first phase and the second phase, an intermetallic compound is interposed between the first phase and the second phase. Thereby, generation | occurrence | production of the battery effect based on the difference in the ionization tendency between Pt of 1st phase and Cu of 2nd phase can be suppressed by the intermetallic compound of 3rd phase. Therefore, since the composite material of the present invention has excellent corrosion resistance, the metallic luster can be maintained for a long time.

  In the present invention, if Au is contained, it is possible to suppress deterioration of corrosion resistance due to the battery effect based on the difference in ionization tendency between Pt and Cu. That is, since Au has an ionization tendency between Pt and Cu, inclusion of Au can suppress the ionization of Cu based on the movement of electrons from Cu to Pt and improve the corrosion resistance of the composite material. it can.

  In the production method of the present invention, it is possible to appropriately produce a composite material that is pink with excellent aesthetics and excellent corrosion resistance.

  The decorative article according to the present invention has a composite material region including the composite material according to the first aspect. In such a composite material region, at least a part of the decorative article of the present invention can be given a pink color having an original metallic luster of Pt. Therefore, aesthetics can be improved while maintaining corrosion resistance.

  In the decorative article according to the present invention, if the composite material region further includes a third phase in contact with the first phase and the second phase, the corrosion resistance of the composite material region can be improved. The metallic luster can be maintained for a long time. In particular, in an ornament that touches human skin, such as an ornament such as a ring, corrosion is likely to proceed due to sweat or the like, and therefore, it is significant to improve the corrosion resistance.

  Hereinafter, the decorative article and the composite material according to the present invention will be described with reference to the drawings, taking a ring as an example. However, the decorative article to which the composite material according to the present invention is applied or the decorative article according to the present invention is not limited to the ring.

  The ring 1 shown in FIGS. 1 (a) and 1 (b) is one in which the entire ring-shaped portion is formed of the composite material 2. The composite material 2 has a maximum value of the reflectance of natural light on the surface in a wavelength range of 560 nm to 640 nm. It is preferable that the reflectance of natural light on the surface of the composite material 2 monotonously decreases, for example, in a wavelength range of 640 nm to 740 nm, and has a minimum reflectance in a wavelength range of 460 nm to 560 nm.

  In addition, about the measurement of the reflectance of this composite material, the sample ground to arithmetic mean surface roughness 10nmRa or less is used.

  The color of the metal is generated by selectively absorbing and reflecting light of a certain wavelength. That is, it is determined by the absorption spectrum or reflection spectrum of light obtained by the electronic structure in the metal. In many metals, the wavelength corresponding to the intrinsic energy of electrons excited by light is not included in the visible light. Therefore, the metal shows a white color. However, Au, Cu, or an alloy thereof shows a specific color because the wavelength corresponding to the intrinsic energy of electrons excited by light is included in the visible light. For example, Au is golden and Cu is red. Therefore, in order to produce the pink color Pt, details will be described later, but it can be achieved by holding the colored metal in the Pt without dissolving it.

  Here, by setting the maximum value of the reflectance of the natural light on the surface in the range of 560 nm or more and 640 nm or less, the reflectance at the red wavelength becomes a peak and the influence of mixing with the wavelengths of other colors can be reduced. That is, if the reflectance has a maximum value at a wavelength of 560 nm or less, the reflectance due to the yellow wavelength component is increased, so that the color is not pink. On the other hand, if the reflectance has a maximum value at 640 nm or more, vivid red is obtained. Shows and does not become a pink coloring with excellent aesthetics. Therefore, since the composite material 2 can emphasize only a desired pink color, it becomes a pink composite material with excellent aesthetics.

  In addition, the reflectance of natural light on the surface monotonously decreases from a wavelength of 640 nm to 740 nm, thereby exhibiting a light pink color. When this is 640 nm or less, the color is slightly yellowish due to the influence of the reflectance due to the yellow wavelength component. Furthermore, when the reflectance is minimal at 460 nm or less compared with the reflectance of natural light on the surface in the wavelength range of 460 nm to 560 nm, the reflectance is gentle including wavelengths from green to yellow. The color tends to become dull, and if it has a minimum value of reflectance at 560 nm or more, it becomes bright red and becomes a color close to copper.

  As shown in FIG. 2, the composite material 2 has a first phase 21, a second phase 22, and a third phase 23. Here, the first phase may be arranged around the second phase, or the second phase may be arranged around the first phase.

  The first phase 21 is a base material of the composite material 2 and contains platinum (Pt) as a main component. The total amount of Pt contained in the first phase 21 is, for example, not less than 40% by weight and not more than 75% by weight of the total composition. When the total amount of Pt is less than 40% by weight, the ratio of copper (Cu), which is the main component of the second phase 22 described later, increases, and the corrosion resistance deteriorates due to the battery effect between Pt and Cu. In addition, it is not preferable because the hue is close to the color of copper. When the total amount of Pt exceeds 75% by weight, the ratio of Cu becomes small, and it becomes difficult to make it pink.

  The Pt weight of the first phase 21 can be calculated by EDS (energy dispersive X-ray analysis) semi-quantitative analysis. That is, characteristic X-rays generated from a depth region of several μm from the surface are detected, each elemental analysis is performed, and the composition can be calculated from the peak intensity.

  The first phase 21 may include at least one of palladium (Pd), rhodium (Rh), ruthenium (Ru), and silver (Ag). By including the exemplified components in the first phase 21, the corrosion resistance of the composite material 2 can be improved. That is, when the first phase 21 includes a noble metal other than Pt, it is possible to suppress the battery effect that occurs between Pt and Cu.

The second phase 22 is dispersed in the first phase 21 and contains copper (Cu) as a main component. Due to the presence of the second phase 22, the composite material 2 contains Cu in addition to Pt, and a part of the second phase 22 is exposed on the surface, so that the composite material 2 becomes pink. Moreover, since the composite material 2 is obtained by dispersing the second phase 22 in the first phase 21, the entire composite material 2 is not an intermetallic compound.
The total amount of Cu contained in the second phase 22 is preferably 25 wt% or more and 60 wt% or less of the total composition of the composite material 2. When the total amount of Cu is less than 25% by weight, the composite material 2 tends to be lighter pink than the intended pink. When the total amount of Cu exceeds 60% by weight, it is difficult to maintain good corrosion resistance over a long period of time.

  The weight of Cu in the second phase 22 can be calculated by EDS semi-quantitative analysis, as in the case of measuring the mass of Pt in the first phase 21.

  Moreover, a part of 2nd phase 22 is exposed on the surface, and it is preferable that the diameter (average value) of such an exposed part is 5-150 micrometers. When the diameter of the exposed portion of the second phase 22 is less than 5 μm, the composite material 2 tends to be light pink. When the diameter of the second phase 22 exceeds 150 μm, the exposed area of the second phase 22 becomes large, so that there is a high possibility that the exposed portion is oxidized when used for a long period of time.

  The second phase 22 may further include at least one of gold (Au), silver (Ag), and palladium (Pd). By including the exemplified components in the second phase 22, the corrosion resistance of the composite material 2 can be improved. That is, when the second phase 22 contains a noble metal other than Cu, the battery effect generated between Pt and Cu can be suppressed. Moreover, the noble metal illustrated, especially Au, can improve the corrosion resistance of the composite material 2 without impairing the pink color by alloying with Cu.

  In addition, by including Au in the second phase 22, a decorative material having excellent corrosion resistance can be obtained. That is, the inclusion of Au causes a change in the color tone of the composite material 2, resulting in a warmer color tone than red that is produced only by Cu. In addition, by including Au, it is possible to obtain a monotonic decrease in reflectance at a wavelength of 640 nm to 720 nm and a minimum value of reflectance at a wavelength of 460 nm to 560 nm. On the other hand, there is a difference in ionization tendency between Pt and Cu, and Cu ions flow out due to the potential difference. For this reason, an Au—Cu alloy in which Au is added to Cu is prepared and used, so that the potential difference is relaxed and the outflow of ionization is suppressed.

  Further, the second phase 22 may contain an element other than the exemplified noble metal, but since the gloss of Al decreases when the content is too large, Al is not included, or the Al content is not the entire content. It is preferable to be less than 5%.

  The third phase 23 contributes to the improvement of the corrosion resistance of the composite material 2 and is formed of an intermetallic compound. The third phase 23 is in contact with both the first phase 21 and the second phase 22. The third phase 23 covers the second phase 22 inside the composite material 2, and the third phase 23 on the surface. Are arranged so as to surround the exposed portion of the second layer 22. That is, the third phase 23 is interposed between the first phase 21 and the second phase 22. In this way, the third phase 23, which is an intermetallic compound, is interposed between the first phase 21 and the second phase 22, whereby ionization between Pt of the first phase 21 and Cu of the second phase 22. The battery effect based on the difference in tendency can be suppressed. As a result, the composite material 2 is excellent in corrosion resistance.

The intermetallic compound of the third phase 23 is typically one in which Pt and Cu are present in an integer ratio, for example, PtCu or PtCu ₃ . Further, in the third phase 23, an intermetallic compound of noble metal other than Pt and Cu, for example, AuCu ₃ or PtAu ₃ may exist. The ratio of Pt to Cu, Au to Cu, and Pt to Au is preferably an integer ratio because it is chemically stable.

  The thickness of the third phase 23 is, for example, 20 μm or less, preferably 0.59 μm or less. When the thickness of the third phase exceeds 0.59 μm, there is a tendency that relatively large irregularities are formed on the surface and it is difficult to give gloss.

  The thickness (width on the exposed surface) of the third phase 23 was determined according to the following definition by photographing an arbitrary cross section of the composite material 2 with a SEM at a magnification of 3500 times in a 20 × 20 μm range. First, five portions including tangent lines that intersect perpendicularly to the surfaces of both the first phase 21 and the second phase 22 are selected from the SEM photograph. Next, the thicknesses in the third phase 23 are respectively measured at the five selected locations, and the average value thereof is calculated to obtain the thickness (width) of the third phase 23.

  The area ratio of the third phase 23 on the surface of the composite material 2 is preferably 1 to 10% in an arbitrary range of 100 μm × 100 μm, and the ratio of the third phase 23 surrounding the second phase 22 in the previous range. Is preferably 85% or more with respect to the length of the outer periphery of the second phase 22.

  In the example shown in FIG. 2, a plurality of second phases 22 containing Cu are arranged in the first phase 21 containing Pt as a main component, but the composite material of the present invention is made of Cu. The second phase may be a base material, and a plurality of first phases mainly composed of Pt may be arranged in the second phase. In this case, the first phase is preferably covered with a third phase that is an intermetallic compound of Pt and Cu.

  Next, the manufacturing method of the composite material 2 of this invention is demonstrated taking the case where the ring 1 is formed by the discharge plasma sintering method as an example.

  First, Pt powder containing Pt and Cu powder containing Cu are mixed at a predetermined ratio to obtain a mixed powder.

  As the Pt powder, for example, it is preferable to use a powder having an average particle diameter of 9 to 150 μm and a purity of 99.9% or more. As the Cu powder, for example, it is preferable to use a powder having an average particle diameter of 5 to 150 μm and a purity of 99.9% or more.

  The weight ratio of the Pt powder in the mixed powder is, for example, 40 wt% or more and 75 wt% or less, and the weight ratio of the Cu powder in the mixed powder is, for example, 25 wt% or more and 60 wt% or less.

  When noble metals other than Pt (Au, Ag, Pd, Rh and Ru) are added to the composite material 2, an alloy of Pt and other metals or an alloy of Cu and other metals is used as Pt powder or Cu powder. In addition to Pt powder and Cu powder, noble metal powder may be mixed. As the noble metal other than Pt, Au is preferably used.

  Next, the mixed powder is filled into a sintered mold and molded into a ring shape, and then a pulsed current is applied to the molded body at a low voltage in a vacuum atmosphere. Thereby, discharge plasma is instantaneously generated in the gaps between the particles of the molded body, and the molded body is sintered.

  Here, the molding pressure when forming the molded body is, for example, 100 MPa or more and 550 MPa. When the molding pressure is less than 100 MPa, pores are easily generated in the composite material 2 and become brittle. When the molding pressure exceeds 550 MPa, stress concentration occurs due to filling of the raw material, leading to damage to the mold. There is. The firing temperature is, for example, 200 ° C. or more and 500 ° C. or less. The firing temperature is set to 200 ° C. or more and 500 ° C. or less because when the firing temperature is lower than 200 ° C., the sintering is poor, and when the firing temperature exceeds 500 ° C., over-firing is performed. Tend to be brittle. The applied pulse voltage is, for example, 4 V or more and 20 V or less. The applied pulse voltage is set to 4 V or more and 20 V or less because when the applied pulse voltage is less than 4 V, sufficient discharge does not occur in the gap between the molded bodies, the target plasma state cannot be achieved, and the applied pulse voltage is 20 V. In the case of exceeding, the possibility of abnormal discharge increases, and in any case, it becomes difficult to obtain the target tissue state.

  In such a discharge plasma sintering method, high energy density and Joule heat are widely applied, thereby enabling efficient sintering with less power consumption. Therefore, the sintering time including the temperature raising and holding time is approximately 5 to 20 minutes, and the entire material does not become an intermetallic compound as in the casting method. A plurality of second phases 22 containing Cu can be dispersed in the first phase 21 and the second phase 22 is coated with a third phase 23 of an intermetallic compound having an appropriate thickness. Alternatively, a plurality of first phases mainly composed of Pt are dispersed in a second phase containing Cu, and the first phase is coated with a third phase of an intermetallic compound having an appropriate thickness. Can be.

  The ring 1 thus obtained is made of the composite material 2 in which the second phase 22 is dispersed in the first phase 21 or the composite material in which the first phase is dispersed in the second phase. As a result, the ring 1 can be a pink one that maintains the neat brightness that is the original metallic luster of Pt.

  Moreover, since the composite material 2 further includes a third phase 23 that is in contact with the first phase 21 and the second phase 22, the third phase that is an intermetallic compound between the first phase 21 and the second phase 22. 23 intervenes. Therefore, the generation of the battery effect based on the difference in ionization tendency between Pt of the first phase 21 and Cu of the second phase 22 can be suppressed by the third phase 23 that is an intermetallic compound. As a result, since the ring 1 has high corrosion resistance, the metallic luster of Pt can be maintained for a long time. In particular, in an ornament that touches human skin, such as an ornament such as the ring 1, since corrosion is likely to proceed due to sweat or the like, it is significant to improve the corrosion resistance.

  Next, an example in which a composite material layer is formed on a part of an ornament will be described using the ring shown in FIG. 3 as an example.

  The ring 3 shown in FIG. 3 is obtained by covering the surface of a core material 30 with a composite material layer 31.

  The core material 30 mainly defines the shape of the ring 3 and is formed in a ring shape having an inner diameter of 13 to 22 mm, an outer diameter of 15 to 24 mm, and a thickness of 2 to 10 mm, for example. Such a core material 30 can be formed by, for example, a casting method or an extrusion molding method. As a material for forming the core material 30, any of noble metals and base metals can be used. However, when it is necessary to consider material cost etc., you may use Ag, Fe, and an alloy containing them.

  The composite material layer 31 is formed of the composite material 2 having the composition state shown in FIG. 2 similarly to the ring 1 described with reference to FIG. That is, in the composite material layer 31, a plurality of second phases 22 containing Cu are dispersed in the first phase 21 containing Pt as a main component, and the second phase 22 contains an intermetallic compound of Pt and Cu. The structure is covered with the third phase 23 (see FIG. 2). The thickness of the composite material layer 31 is, for example, 0.03 to 0.1 μm. Of course, in the composite material layer 31, the first phase containing Pt as the main component is dispersed in the second phase containing Cu, and this first phase is covered with the third phase containing the intermetallic compound of Pt and Cu. It may be an organized organization.

  Such a ring 3 is formed by forming a molded body in which a core 30 formed in advance is inserted with a mixed powder of Pt powder and Cu powder, and then firing the molded body by a discharge plasma sintering method. Can be formed.

  Also in such a ring 3, the composite material layer 31 made of the composite material 2 in the tissue state shown in FIG. 2, or the composite material layer 31 in which the first phase covered with the third phase is dispersed in the second phase. Is formed on the surface.

  Next, another example of the decorative article according to the present invention will be described with reference to FIGS.

  The necklace 4 shown in FIG. 4 includes a head 40 and a chain 41, and at least one of the head 40 and the chain 41 has at least the rings 1 and 3 described above (see FIGS. 1 to 3). The composite material layer has the same structure as that of the reference material. The head 40 or the chain 41 may be entirely formed of the composite material of the present invention, or the surface of the core material may be covered with the composite material of the present invention. When the composite material layer is formed on the surface of the core material in the head 40 or the chain 41, the thickness of the composite material layer is set to 0.03 to 0.1 μm, for example.

  In the necklace 4, the form of the head 40 and the chain 41 can be variously changed, and the head 40 may be omitted and the necklace 4 may be configured as a necklace.

  The bracelet 5 shown in FIG. 5 is formed by connecting a plurality of pieces 50 in a ring shape, and at least the surface layer of each piece 50 has the same structure as the rings 1 and 3 described above (see FIGS. 1 to 3). The composite material layer is in a state. The whole piece 50 may be formed of the composite material of the present invention, or the surface of the core material may be coated with the composite material of the present invention. When the composite material layer is formed on the surface of the core material in the piece 50, the thickness of the composite material layer is set to 0.03 to 0.1 μm, for example.

  The bracelet 5 can be variously changed with respect to the shape of the piece 50, and the bracelet of the present invention does not necessarily have to be composed of a plurality of pieces.

  In the timepiece 6 shown in FIG. 6, at least the surface layer of the belt 60 is a composite material layer having the same structure as the rings 1 and 3 (see FIGS. 1 to 3) described above. The belt 60 may be entirely formed of the composite material of the present invention, or the surface of the core material may be coated with the composite material of the present invention. In the timepiece 6, the side edge 61 may be formed of the composite material of the present invention, and in this case, the side edge 61 may be entirely formed of the composite material of the present invention. The surface may be coated with the composite material of the present invention. When the composite material layer is formed on the surface of the core material at the belt 60 or the side edge 61, the thickness of the composite material layer is set to 0.03 to 0.1 μm, for example.

  The timepiece 6 can be variously changed in the shape of the belt 60, the side edge 61, and the like, and the present invention can be applied to a timepiece having a form other than that illustrated.

  In the glasses 7 shown in FIG. 7, at least the surface layer of the frame 70 is a composite material layer in a tissue state similar to the rings 1 and 3 described above (see FIGS. 1 to 3). The frame 70 may be entirely formed of the composite material of the present invention, or the surface of the core material may be coated with the composite material of the present invention. When a composite material layer is formed on the surface of the core material in the frame 70, the thickness of the composite material layer is set to 0.03 to 0.1 μm, for example.

  The glasses 7 can be variously modified with respect to the shape of the frame 70 and the like, and the present invention can be applied to a timepiece having a form other than that illustrated.

  In the fountain pen 8 shown in FIG. 8, at least one surface layer of the pen tip 80 is a composite material layer having a structure similar to that of the rings 1 and 3 described above (see FIGS. 1 to 4). The pen tip 80 may be entirely formed of the composite material of the present invention, or may be one in which the surface of the core material is coated with the composite material of the present invention. When the composite material layer is formed on the surface of the core material at the pen tip 80, the thickness of the composite material layer is set to 0.03 to 0.1 μm, for example. In the fountain pen 8, in addition to the pen tip 80 or instead of the pen tip 80, at least the surface layer in other parts such as the clip 81 may be formed as a composite tissue layer.

  The shape of the fountain pen 8 can be variously changed with respect to the shape of the nib 80, the clip 81, and the like, and the present invention can be applied to a timepiece having a form other than the illustrated one.

  4 to 8, that is, the composite material layer in the necklace 4, bracelet 5, watch 6, glasses 7 and fountain pen 8, the second phase containing Cu contains Pt as a main component. One phase may be arranged, and the first phase may be in a textured state surrounded by a third phase containing an intermetallic compound of Pt and Cu.

The present invention is not limited to the embodiments described above, and can be variously modified. For example, the third phase 23 of the composite material 2 (composite material layer 6) may be omitted as long as the corrosion resistance and strength according to the application can be ensured. It may be generated by a method other than the spark plasma sintering method by appropriately setting the conditions. For example, although some voids are generated, it can also be generated by gradually raising the temperature to 500 ° C. under vacuum conditions of 1.33 × 10 ⁻² Pa by vacuum firing and firing at this temperature for 30 minutes. it can.

  The present invention is not limited to the above-described rings, necklaces, bracelets, watches, and glasses, but can be applied as a part or all of other decorative items. Examples of other ornaments to which the present invention can be applied include tableware, figurines, golf clubs, mobile phones, buttons, and the like. Further, the composite material of the present invention is not limited to a decorative article, and can also be used as a target material in film formation by a PVD (physical vapor deposition) method.

  In this example, the wavelength characteristic of the reflectance of natural light on the surface of a sample made of a Pt—Cu composite material was evaluated.

(Sample preparation)
The sample was formed into a ring shape by forming the mixed powder shown in Table 1 below into a ring shape in a sintering mold and then firing it under the conditions shown in Table 1 below by a discharge plasma sintering method. The sample size was set such that the inner diameter was 19.8 mm, the outer diameter was 23 mm, and the thickness was 5 mm. The composition of each element in the mixed powder was as shown in Table 1 below.

On the other hand, a sample formed by a casting method was produced as a comparative example. The composition of the sample of the comparative example is as follows. After the mixed powder having the composition shown in Table 2 below is melted at 1700 ° C., it is poured into a predetermined mold held at 700 ° C., and the mold is rotated at a rotational speed of 550 rpm. It produced by shape | molding.

(Wavelength characteristics of reflectance)
The reflectance was measured using “CM-3700d” (Minolta Co., Ltd.) for a sample whose surface was mirror-finished. The mirror surface processing was performed by polishing with a buff so that the arithmetic average surface roughness Ra was in the range of 0.030 μm to 0.054 μm. The reference light source was set to “D65” as “standard illuminant for colorimetry (standard light) and standard light source” from JIS standard (Z-8720), and the viewing angle was set to 10 °. The wavelength characteristic was evaluated as the reflectance of diffused light when the peak wavelength was changed in the range of 360 nm to 740 nm.

Regarding the measurement results of the reflectance, sample Nos. Made of Pt and Cu were used. 1-No. 9 is the same as the sample No. 9 containing Au and Pd in addition to Pt and Cu. 10-No. 14 is shown in FIG. 10, and Comparative Examples 1 and 2 prepared by the casting method are shown in FIG. Further, regarding the measurement results of the minimum and maximum values of the reflectance in the wavelength characteristics and the wavelength at which the reflectance starts monotonically decreasing, the sample No. 1-No. Table 10 shows the results for 10 and Table 4 shows the comparative examples. In FIGS. 9 and 10, the maximum value of the present application is indicated by ▲ and the minimum value is indicated by ●.

(Consideration of results)
Sample No. produced by the spark plasma sintering method. 1-No. 17 is a pink color having excellent aesthetics, and has a maximum reflectance value in the wavelength range of 580 nm to 630 nm in the wavelength characteristic of reflectance. Sample No. 1-No. 17 also had a minimum reflectance in the wavelength range of 460 nm to 560 nm. Furthermore, sample no. 1-No. In FIG. 17, there was a monotonic decrease in wavelength that could be seen after taking the maximum value, but it generally showed a monotonic decrease trend from 640 nm.

  Sample No. containing no Au was used. 1-No. 9 and sample No. containing gold. 10-No. When comparing with No. 15, there was a tendency that the minimum value and the maximum value shift to the short wavelength side by containing Au.

  On the other hand, in Comparative Examples 1 and 2 prepared by the casting method, no remarkable peak was observed in the wavelength dependence of the reflectance, and the wavelength dependence of the reflectance decreased monotonously from 360 nm. This is because, when produced by the casting method, in the Pt—Cu phase diagram, the complete solid solution type is in a completely solid solution relationship. For this reason, since Pt or Cu does not exist as a phase, it is considered that red coloring cannot be expected by the casting method.

  On the other hand, in the discharge plasma sintering, the target shape can be obtained with a minimum reaction by heating rapidly while applying pressure. For this reason, only surface diffusion occurs between Pt and Cu, and it is considered that a pink color is obtained when Cu and Pt are not dissolved but exist as phases.

  Further, when the conditions of the discharge plasma sintering (molding pressure and sintering temperature) are different, the wavelength dependency (maximum value and minimum value) of the reflectance of the composite material changes. That is, a desired wavelength characteristic can be obtained with respect to the reflectance by appropriately selecting the conditions of the discharge plasma sintering. In the range examined this time, materials having excellent aesthetics were obtained for all the samples. As can be seen from Table 1, at least the molding pressure (pressing force) was 100 MPa to 550 MPa and the firing temperature was 200 ° C. to 500 ° C. If so, good results can be obtained.

  In this example, the structure state, the color of the Pt—Cu composite material, and the corrosion resistance in the cross section of the sample made of the Pt—Cu composite material were evaluated.

(Sample preparation)
The sample was formed into a ring shape by forming a mixed powder having the composition shown in Table 5 below into a ring shape in a sintering mold at 300 MPa and then firing it at 300 ° C. by a discharge plasma sintering method. The sample size was set such that the inner diameter was 19.8 mm, the outer diameter was 23 mm, and the thickness was 5 mm.

(Evaluation of organizational status)
The structure of the sample was determined by observing the presence and composition of the first phase 21, the second phase 22 and the third phase 23 (see FIG. 2), and the covering state of the second phase 22 by the third phase 23. .

  The presence of the first to third phases 21 to 23 and the covering state of the second phase 22 by the third phase 23 were performed by SEM observation. The compositions of the first to third phases 21 to 23 were confirmed by performing EDS semi-quantitative analysis.

  The evaluation results of the tissue state are shown in Table 6 below. In Table 6 below, a case where it is confirmed that the second phase 22 is covered with the third phase 23 is marked with a circle.

(Color evaluation)
The color was evaluated visually. The color evaluation results are shown in Table 6 below. In Table 6 below, a beautiful pink color is marked with ◎, and a moderate pink color is marked with ○.

(Evaluation of corrosion resistance)
The corrosion resistance of the sample was determined by visually observing the degree of discoloration and the surface condition after half-immersing the buffed sample in artificial sweat and leaving it in an atmosphere of 40 ± 5 ° C. for 30 minutes.

  The artificial sweat is 9.2 g / L of sodium chloride, 0.8 g / L of sodium sulfide, 1.7 g / L of urea, 0.18 mL / L of aqueous ammonia, 0.22 g / L of sucrose, 1.1 mL / L of lactic acid, pure Prepared with 1 L of water.

The evaluation results of the corrosion resistance are shown in Table 6 below. In Table 6 below, the symbol ◎ indicates a case where the corrosion resistance is particularly excellent, the symbol ◯ indicates a case where the corrosion resistance is excellent, and the symbol Δ indicates a case where corrosion resistance is recognized but there is no practical problem.

(Consideration of results)
As can be seen from Table 6, regarding the color, sample No. which is a composite material according to the present invention is used. 1-4 showed the visible pink color. This is the sample No. In 1-4, the first phase (Pt) and the second phase (Cu) are not completely dissolved, and the second phase exists independently in the first phase, or the second phase exists in the second phase. This is probably because one phase exists independently. Further, in the third phase, AuCu ₃ is present as an intermetallic compound in addition to Pt—Cu, which is considered to affect the color of the composite material. Sample No. The total amount of Pt of 1 to 4 is 40% by weight or more and 75% by weight or less in the entire composition, and it is considered that a beautiful pink color can be obtained at least within this range.

  Regarding the corrosion resistance, Sample No. In Nos. 1 to 4, corrosion enough to cause practical problems was not observed. This is the sample No. 1-4 are considered to be because the intermetallic compound is in contact with the first phase and the second phase, and is present as the third phase covering the second phase or the first phase. That is, the presence of a third phase (intermetallic compound) between the first phase (Pt) and the second phase (Cu) causes an ionization tendency between the first phase Pt and the second phase Cu. It is considered that the battery effect based on the difference is suppressed and the corrosion resistance is improved as compared with the case where the third phase does not exist. Sample No. In 1-4, Au is contained in the 2nd phase and the 3rd phase, and it is thought that corrosion resistance improves also in this point.

  From the above results, Sample No. As in 1-4, in the structure state, the second phase is arranged in the first phase, or the first phase is arranged in the second phase, and the intermetallic compound in contact with both the first phase and the second phase By allowing the third phase to exist in a state of covering the second phase, a composite material having a pink color and excellent corrosion resistance can be obtained. In particular, even in the case of a decorative product that requires more severe corrosion resistance, such as a ring, the sample No. 1 of the present invention is used. 1 to 4 can maintain a pink metallic luster over a long period of time.

Fig.1 (a) is a whole perspective view of the ring which is an example of the ornament which concerns on this invention, FIG.1 (b) is sectional drawing which follows the IIb-IIb line | wire of Fig.1 (a). It is a schematic diagram which shows an example of the structure | tissue state of the composite material which concerns on this invention. It is sectional drawing which shows the other example of the ring which is an example of the ornament which concerns on this invention. It is a front view which shows the necklace which is an example of the ornament which concerns on this invention. It is a front view which shows the bracelet which is an example of the ornament which concerns on this invention. It is a front view of a timepiece which is an example of a decorative article according to the present invention. It is a whole perspective view which shows the spectacles which is an example of the ornament which concerns on this invention. It is a front view which shows the fountain pen which is an example of the ornament which concerns on this invention. Sample No. 1 in Example 1 1-No. 9 is a graph showing the measurement result of the reflectance of 9; Sample No. 1 in Example 1 10-No. It is a graph which shows the measurement result of the reflectance of 14. 6 is a graph showing the measurement results of the reflectances of Comparative Examples 1 and 2 in Example 1.

Explanation of symbols

1, 3 Ring 2 Composite material 21, 21 'First phase 22, 22' Second phase 23, 23 'Third phase 31 Composite material layer (composite material region)
4 necklace 5 bracelet 6 watch 7 glasses 8 fountain pen

Claims (12)

  A range having one or a plurality of first phases containing Pt as a main component and one or a plurality of second phases containing Cu, and having a maximum value of the reflectance of natural light on the surface ranging from 560 nm to 640 nm A composite material characterized by   The composite material according to claim 1, wherein the reflectance of natural light on the surface monotonously decreases in a wavelength range of 640 nm to 740 nm.   The composite material according to claim 1 or 2, wherein the minimum value of the reflectance of natural light on the surface is in the range of a wavelength of 460 nm or more and 560 nm or less.   The composite material according to any one of claims 1 to 3, wherein the Pt content is 40% by weight or more and 75% by weight or more in the total composition.   The composite material according to any one of claims 1 to 4, wherein the plurality of second phases are arranged in the first phase.   The composite material according to any one of claims 1 to 4, wherein the plurality of first phases are arranged in the second phase.   7. The method according to claim 1, further comprising a third phase in contact with both phases between the first phase and the second phase and including an intermetallic compound formed of Pt and Cu. The composite material described.   The composite material according to claim 7, wherein the third phase covers the first phase or the second phase. A method for producing a composite material according to any one of claims 1 to 8,
A method for producing a composite material, comprising mixing a metal particle containing Pt and a metal particle containing Cu to form a compact, and subjecting the compact to spark plasma sintering in a vacuum atmosphere.   The method for producing a composite material according to claim 9, wherein the firing temperature is 200 ° C or higher and 500 ° C or lower.   The method for producing a composite material according to claim 9 or 10, wherein a molding pressure when forming the molded body is 100 MPa or more and 550 MPa or less. A decorative article having a composite material region formed by a composite material,
The decorative article according to any one of claims 1 to 8, wherein the composite material is the one according to any one of claims 1 to 8.

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