JP2010115657A - Binderless powder for surface hardening - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide powder for surface hardening capable of realizing the binderless surface hardening with excellent oxidation resistance, high hardness and high dispersibility. <P>SOLUTION: The binderless powder for surface hardening includes compound carbide particles synthesized in the metal dip dispersion of carbon and W and Ti as major metal components, or compound carbide particles with W, Ti and M containing a trace of sub metal component M consisting of Nb, Ta, Zr and V as necessary, wherein the content of Co, Ni and Fe is reduced. The binderless particle powder has the average grain size of 20-200 μm, and excellent oxidation resistance, high hardness and high dispersive properties. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is, for example, a composite carbide particle of W and Ti or a composite of W, Ti, and sub-metal component M that has excellent oxidation resistance and has high hardness and high dispersibility suitable for overlaying, thermal spraying, etc. The present invention relates to a binderless powder for surface hard wearing made of carbide particles.

Conventionally, as a manufacturing method of carbide particles,
(B) Synthesis method by diffusion of metal and carbon in metal bath (so-called menstral method)
(B) Thermal synthesis method by solid phase / vapor phase diffusion of metal powder and carbon powder,
(C) Reduction carbonization of metal oxide powder and carbon powder, vapor phase carbonization of metal powder,
(D) a production method utilizing a reaction between a metal halide and a hydrocarbon,
(E) Mechanical alloying, etc.
Various methods are known.
However, when these carbide particles are used for surface hardening, the particle diameter of the hard powder particles is preferably several tens of μm or more and high density, but the above (b) to (e) Since the product obtained by the manufacturing method is fine particles, it is necessary to add a binder metal and sinter by powder metallurgy.
For example, in the prior art shown as Patent Document 1, a binder component such as Co, Ni, or Fe is added to and mixed with the hard particles, and the particles are granulated and sintered to a predetermined particle size, or sintered, pulverized, and adjusted. By depositing the granulated particles by PTA (Plasma Transferred Arc) welding using plasma gas, a build-up portion in which hard particles are dispersed and distributed is formed on the surface of the base material.
Further, as another conventional technique, for example, a build-up portion has been formed by adding the granulated composite powder to a molten pool formed on the surface of a base material by arc heat.
By the way, in each of the above prior arts, as the overlaying powder, it is necessary to use a mixed powder obtained by adding a binder component made of Co, Ni, Fe to hard particles such as WC and TiC, In the built-up portion, hard particles such as WC and TiC are submerged during the build-up due to the difference in specific gravity (for example, the specific gravity of WC is about 15.7, while the specific gravity of TiC is about 4.9). Since the floating phenomenon occurs and the hard particles are not uniformly dispersed, there is a drawback that the structure and hardness distribution of the built-up portion are likely to be uneven.
In addition, when overlaying is performed using a matrix material such as stainless steel, the hard particles are dissolved into the matrix material and the hard particle content of the overlay is reduced, so that the entire overlay part As a result, there was a problem that the increase in hardness was not sufficient.
Japanese Unexamined Patent Publication No. 7-32189

  Accordingly, the present invention provides a hard powder for surface hard wearing that does not cause sinking or lifting during overlaying, has a small amount of hard particles to be dissolved in the matrix material, and further has a binder such as Co, Ni, or Fe. An object of the present invention is to provide a binderless powder for surface hard wearing, which does not require the use of ingredients, has excellent oxidation resistance, and can form a hard dressing with high hardness and uniform dispersion of hard particles. It is.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research on the relationship between the type of hard powder and its production method, and obtained the following knowledge.

  For the WC particles, TiC particles or NbC particles as the surface hardening powder, for example, a synthesis method by diffusion of metal and carbon in a metal bath consisting of the schematic steps shown in FIG. Etc.), and it has been known that, when these materials are built up as hard wearing powders, a built-up portion having a predetermined hardness is formed.

  By the way, when the present inventors manufactured composite carbide of W and Ti (hereinafter referred to as (W, Ti) C) particles, not WC particles alone or TiC particles alone, by the above-mentioned menstrual method, As a result, it was found that (W, Ti) C particles having extremely excellent characteristics can be obtained.

  That is, the (W, Ti) C particles obtained by the menstral method are particles having a cubic crystal structure, almost a spherical shape, and a coarse particle size (20 to 200 μm). Even when this is used as a powder for hard wearing, it is not necessary to add and mix binder components such as Co, Ni, Fe, etc. Further, for example, (W, Ti ) Subsidence and lifting of C particles are extremely low, and hard components are not so much dissolved in a matrix material such as stainless steel.

  Therefore, according to the powder for surface hardening of the present invention (Claim 1), not only the use of a binder component is unnecessary, but also excellent oxidation resistance as compared with the characteristics of the conventional built-up part, It is possible to obtain a hardened built-up with high hardness in which hard particles in the built-up portion are uniformly dispersed.

  Further, as described above, the present inventors also have a composite carbide of W, Ti, and M (wherein M is one or more of metal components composed of Nb, Ta, Zr, and V) (hereinafter referred to as ( W, Ti, M) C. It should be noted that both (W, Ti) C and (W, Ti, M) C are collectively referred to as (W, Ti (M)) C) for the particles. As a result of the production by the method, it was found that (W, Ti, M) C particles having characteristics more excellent than the (W, Ti) C particles can be obtained as the hard powder.

That is, as in the case of the (W, Ti) C particles, the obtained (W, Ti, M) C particles have a cubic structure and are substantially spherical and have a coarse particle size. Is used as a hard powder, it is not necessary to add and mix binder components such as Co, Ni, Fe, etc., and (W, Ti, M) C particles sink into the build-up part In addition, it was confirmed that there was little penetration into the matrix material, and further, the secondary metal component M was added in a total amount of 20% by weight or less, preferably 10 to 20% by weight. It was also confirmed that the effect was achieved.
The sub-metal component M is composed of one or more of Nb, Ta, Zr, and V, but the Nb component or Ta component improves the wettability with the matrix component, and the Zr component or V component It has the effect of increasing the hardness and strengthening the matrix, and further improves the toughness, hardness and the like of the (W, Ti, M) C particles.

  Therefore, according to the surface-hardening powder of the present invention (Claim 2), in addition to the use of a binder component, good oxidation resistance, high hardness, and high dispersion of the built-up portion, in terms of toughness, hardness, etc. It is possible to form a hardfacing with more excellent characteristics.

This invention has been made based on the above findings,
“(1) Composed of composite carbide particles composed mainly of W and Ti synthesized by diffusion of metal and carbon in a metal bath, and the total content of metal components consisting of Co, Ni, and Fe is less than 3% by weight. A binderless particle powder for surface wear that has an oxidation resistance, high hardness, and high dispersibility, and has an average particle size of 20 to 200 μm.
(2) W, Ti synthesized by diffusion of metal and carbon in a metal bath, and sub-metal component M (where M is one or more metal components composed of Nb, Ta, Zr, V) Is composed of composite carbide particles containing as a main metal component, the metal component consisting of Co, Ni and Fe is suppressed to a total content of 3% by weight or less, and the sub metal component M is contained in a total content of 20% by weight or less. And the binderless particle | grain powder for surface hardening which has an oxidation resistance, high hardness, and high dispersibility whose average particle diameter is 20-200 micrometers. "
It has the characteristics.

  Hereinafter, the present invention will be described more specifically and in detail.

  In short, “synthesized by diffusion of metal and carbon in a metal bath” means that “carbide is precipitated in the metal bath, the metal content is decomposed by acid treatment, and excess carbon is removed by beneficiation to obtain the desired carbide. The technical meaning of “obtained by the production method (Mentrum method)” is as follows. First, the production of carbide by the Mestram method will be described.

  As shown in the process diagram of FIG. 1, the Mestram method uses a raw material composed of Fe—carbide-forming metal (or Fe + carbide-generating metal) + C and a molten metal bath at 2000 ° C. or higher (in addition to Fe, Mn, Co , Ni, Cu, Al, etc.) may be included in the heat treatment furnace, followed by acid treatment, decomposition of carbides other than the target product in addition to Fe, and then washing with water in the beneficiation process.・ Sieving and specific gravity separation to obtain high-quality target carbides, at the same time, impurities are separated and removed, followed by further drying and sieving to obtain a desired carbide.

  In the present invention, in the above-described menstral method, various types and compositions of blending raw materials were changed to produce various carbides. As a result, W and Ti were main metal components, and the weight ratio was WC / TiC = 60/40 to 70. (W, Ti) C particles corresponding to a composition ratio of / 30, and further, a sub-metal component M (where M is one or more of metal components composed of Nb, Ta, Zr, V) ) In a total content of 20 wt% or less (preferably 10 to 20 wt%), (W, Ti, M) C particles could be obtained.

All of these carbide particles obtained by the above-mentioned menstrual method had a roughly spherical particle shape and an average particle diameter of 20 to 200 μm.
The hardness (Hv) of the obtained (W, Ti (, M)) C particles is approximately 2600, and the specific gravity is determined by the composition and blending, although there are some changes depending on the blending ratio of W, Ti, and M. Therefore, when the above (W, Ti (, M)) C particles are used as the surface hard wear particle powder, the hard particles are not submerged or lifted up in the built-up portion. A uniform hard particle distribution is formed over the entire built-up portion, and as a result, a built-up portion having a uniform hardness distribution and a uniform built-up structure is formed.

  In addition, the (W, Ti (, M)) C particles can form a built-up portion without adding and mixing binder components such as Co, Ni, and Fe, so that binder components such as Co, Ni, and Fe are used. Compared to a conventional built-up portion using a binder, there is no decrease in hardness due to the use of a binder, and a built-up portion with higher hardness can be formed. In addition, a small amount of Co, Ni, Fe may be contained in (W, Ti (, M)) C particles mainly due to carry-in from the raw material, if the total content is 3 wt% or less, Since there is no significant effect on the build-up portion characteristics, these metal components are allowed to be contained within a total content of 3% by weight or less, but the content exceeds 3% by weight. Then, the increase in the soft component (Co, Ni, Fe) in the build-up part causes a decrease in the hardness of the build-up part, so that from the Co, Ni, Fe in the (W, Ti (, M)) C particles The total content of the metal components must be suppressed to 3% by weight or less (that is, (Co + Ni + Fe) / (Co + Ni + Fe + W + Ti (+ Nb + Ta + Zr + V)) ≦ 0.03).

Furthermore, since the (W, Ti (, M)) C particles are hard particles having a substantially spherical shape and a large particle size, when the matrix material such as stainless steel is used for overlaying, Since the (W, Ti (, M)) C particles are less soluble, the hardness is not lowered by the penetration of the hard component, and as a result, the high hardness can be maintained throughout the built-up portion.
In addition, the low penetration of the hard component means that there is no significant change in the matrix hardness of the built-up part due to the presence of the hard component. Therefore, by appropriately selecting the hardness of the matrix material to be used, It is possible to easily and widely adjust the matrix hardness of the part within the desired hardness range.

  In addition, as a production method other than the menstrual method, there are, for example, solid solution synthesis of WC + TiC, synthesis by W + Ti + C, W + oxidized Ti + C, oxidized W + oxidized Ti + C, and the like. As a result, it was not possible to obtain coarse and high-density particles having an average particle diameter of 20 to 200 μm according to the present invention by any method. Or the coarse and high-density particle | grains of 20-200 micrometers were hardly formed.

  The (W, Ti (, M)) C particles obtained by the menstrual method are adjusted so that the particle size is adjusted by sieving so that all particles become spherical particles having an average particle size of 20 μm or more. Is less than 20 μm, the amount of penetration into the matrix material is increased, the hardness of the built-up part as a whole is reduced, or the hardness of the built-up part is difficult to adjust, while the average particle size is more than 200 μm, Since the filling ratio of the built-up portion is reduced (density is reduced) and tends to become brittle, the average particle diameter of (W, Ti (, M)) C particles is determined to be 20 to 200 μm.

  The surface-hardening particle powder of the present invention is composed of composite carbide particles containing W and Ti (and sub-metal component M) as main metal components, and has an average particle size of 20 to 200 μm with reduced contents of Co, Ni and Fe. This is a binderless particle powder for surface wear with oxidation resistance, high hardness and high dispersibility synthesized by diffusion of metal and carbon in a metal bath. In this case, the built-up part has excellent oxidation resistance, and the hard part does not float and sink, and the hard (W, Ti (, M)) C particles do not appear in the built-up part. Has a homogeneous build-up structure because it is uniformly dispersed, and further, since a metal component consisting of Co, Ni, and Fe is not used as a binder, the hardness of the particles can be increased, and further, hard ( W, Ti (, M)) C particles are spherical coarse Since it is a particle and has low penetration into the matrix, it retains high hardness, or by selecting a matrix material, it is possible to easily adjust the matrix hardness of the built-up part to a desired value. It can be said that the (W, Ti (, M)) C particle powder is very suitable for surface hard wearing such as thermal spraying.

  Hereinafter, the present invention will be described in detail based on examples.

As an example of the present invention (Claim 1), (W, Ti) C particle powder shown in Table 1 was produced by the Menstral method.
That is, in FIG. 2, raw materials blended at a ratio of 25 wt% Fe—Ti alloy (17 kg), W powder (23 kg) and carbon powder (5 kg) were charged into a direct current heating type arc heat treatment furnace. Carbide is synthesized in a molten metal bath at ℃ or higher, then acid-treated with hydrochloric acid at 80 ℃, decomposes carbides other than the target product in addition to Fe, and then washed with water, sifted, and specific gravity beneficiation in the beneficiation process The impurities are separated and removed, followed by further drying and sieving, and a composite carbide of tungsten and titanium corresponding to WC / TiC = 60/40 wt% with an average particle size of 20 to 200 μm ((W, Ti ) C) Particle powder was obtained.
The average particle diameter (μm), hardness (Hv), specific gravity, oxidation resistance (oxidation start temperature, ° C.) and Co measured for the obtained (W, Ti) C particle powder (hereinafter referred to as Invention Example 1). Table 1 shows the values of the total content (wt%) of Ni, Ni, and Fe.
The oxidation start temperature (° C.) was determined by measuring TG-DTA in air with a differential thermobalance.

  For comparison, NbC, WC, TiC, cemented carbide, and cermet powder particles were also produced by the Mestram method, and the average particle diameter (μm), hardness (Hv), specific gravity, and oxidation resistance (oxidation start temperature) of the particle powder. .Degree. C.) and the total content (wt%) of Co, Ni and Fe. The values are also shown in Table 1.

Next, using the (W, Ti) C particle powder of Example 1 of the present invention, a PTA build-up test was performed by overlay welding using PTA (Plasma Transferred Arc) welding using plasma gas.
Under the welding conditions shown in Table 2, welding test pieces having dimensions and shapes shown in FIG. 3 were prepared by PTA overlay welding.
For comparison, the NbC, WC, TiC, cemented carbide, and cermet particle powders (Comparative Examples 1 to 5) manufactured by the menstral method are also subjected to the PTA overlay test under the same conditions as in the above-described Invention Example 1. Carried out.

  FIG. 4 (a) shows a cross-sectional photograph of the built-up portion formed according to Example 1 of the present invention, and FIG. 5 (a) shows the structural state of the built-up portion observed by a scanning electron microscope. 4 (b) to 4 (f) show cross-sectional photographs of the built-up portion formed by 1 to 5, respectively, and FIG. 5 (b) to (f) show the tissue state of the built-up portion observed by a scanning electron microscope, respectively. Shown in f).

First, as seen in Invention Example 1 in Table 1, the (W, Ti) C particle powder of Invention Example 1 has the second highest hardness and oxidation start temperature next to TiC powder, and its specific gravity is 8.3. And uniform (naturally).
And when the (W, Ti) C particle powder of Invention Example 1 is used as a powder for hard wearing, as shown in FIG. It has a uniform structure and a highly dispersed structure in which hard particles are uniformly dispersed, and as shown in FIG. 5 (a), the matrix hardness is 400 to 600, and the particle hardness is 2500 to 2800. The raised portion has high hardness and excellent oxidation resistance.

On the other hand, as shown in Table 1 as Comparative Example 3, the TiC powder itself has a very high hardness of 2900 Hv and an oxidation start temperature of 840 ° C., and both the hardness and the oxidation resistance are (W, Ti) C of the present invention. As shown in FIG. 5 (d), the build-up portion where PTA build-up welding was performed using TiC particle powder has a matrix hardness of 300 to 550 and a particle hardness of 2800. It is -3200, Comprising: The build-up part has high hardness.
However, as shown in FIG. 4 (d), in the built-up portion formed using the TiC particle powder, a hard particle lift phenomenon occurs, and the TiC hard particles are unevenly distributed above the built-up portion, A matrix material (SUS316L) is unevenly distributed in the vicinity of the base material, and a highly dispersed structure / uniform structure over the entire built-up portion is not obtained. Therefore, when TiC is used as a hard wearing particle powder, the build-up portion hardness becomes non-uniform due to the heterogeneous distribution of hard components, and a reliable build-up portion cannot be obtained.

  Further, as shown in Table 1, the other particle powders NbC, WC, carbide, cermet (Comparative Examples 1, 2, 4, 5) are compared with the (W, Ti) C particles of Example 1 of the present invention. Both hardness and oxidation resistance were inferior.

Furthermore, when the build-up portion is formed by PTA welding using other particle powder, for example, in the case of NbC particle powder, as shown in FIG. 4B, uniform dispersion of hard particles in the build-up portion However, as shown in FIG. 5 (b), the matrix hardness and particle hardness of the built-up portion are low, and the oxidation resistance is low (in Table 1, the oxidation start temperature is 580 ° C.). It cannot be said that it has satisfactory characteristics as a wearing particle powder.
In the case of the WC particle powder, as shown in FIG. 4 (c), segregation of hard particles occurs in the built-up portion, so that a non-uniform build-up structure is exhibited, and as shown in FIG. 5 (c). In addition, while the particle hardness is low, the matrix hardness is increased due to the penetration of the hard particles, but the hardness of the built-up part as a whole is insufficient, and the oxidation resistance is also low. It does not have satisfactory characteristics.
In the case of the super hard particle powder, as shown in FIG. 4 (e), most of the super hard particles are dissolved (melted) in the built-up portion, and as shown in FIG. 5 (e). As described above, although the hardness of the matrix increases due to the penetration of the super hard particles, the hardness of the entire built-up portion is insufficient and the oxidation resistance is low, so that it is not satisfactory as a powder for hard wearing particles.
In the case of the cermet particle powder, as shown in FIG. 4 (f), most of the cermet particles are dissolved (melted) in the built-up portion, and as shown in FIG. 5 (f). In addition, since the hardness of the built-up part as a whole is insufficient, it is not satisfactory as a powder for hard wearing.

Based on the results of the PTA test, hard particle hardness, oxidation resistance, residual amount of hard particles in the overlay (inversely proportional to penetration), dispersibility (uniform distribution of hard particles in the overlay), matrix hardness From the point of view, Table 3 shows the appropriate comprehensive evaluation as the particle powder for surface hard wearing.
According to Table 3, the (W, Ti) C powder of the present invention (Claim 1) has high hardness of the particles themselves, little penetration into the matrix, high dispersibility in the built-up portion, and oxidation resistance. Therefore, it can be seen that it is suitable as a particle powder for surface hard wearing.

Next, as an example of the present invention (Claim 2), the raw materials shown in Table 4 are used, and the sub-metal component M is any one or more of metal components composed of Nb, Ta, Zr, and V. The contained (W, Ti, M) C particle powder was produced by the menstrual method shown in FIG.
Table 5 shows the characteristic values measured for the obtained (W, Ti, M) C particle powder (referred to as Invention Examples 2 to 6).
In addition, using the (W, Ti, M) C particle powders of Invention Examples 2 to 6, the same conditions as in Example 1 (welding conditions shown in Table 2, welding test pieces having dimensions and shapes shown in FIG. 3). A PTA overlay test was conducted.
Similar to Example 1, the particle hardness and matrix hardness were measured, and the residual amount and dispersibility of the hard particles in the built-up part were investigated by cross-sectional observation and structure observation of the built-up part. The results are shown in Table 6.

  As described above, from the results shown in Table 3, Table 6, FIG. 4, and FIG. 5, the (W, Ti) C particle powder or (W, Ti, M) C particle powder of the present invention was used for overlaying. In this case, the built-up portion has excellent oxidation resistance, and the built-up portion does not cause hard particles to rise or sink, and the hard particles are uniformly dispersed. When the structure is formed, and when building up, it is not necessary to use a metal component consisting of Co, Ni, Fe as a binder, the hardness of the built-up part can be increased. Spherical coarse particles that have low penetration into the matrix, maintain high hardness, or by selecting a matrix material, the matrix hardness of the built-up part can be easily adjusted to a desired value, For surface wear such as deposition and thermal spraying Said to be preferred particles as a child powder.

It is the schematic of the manufacturing process of the carbide | carbonized_material by the synthesis method (Mentstral method) by the diffusion in the metal bath of a metal and carbon. The manufacturing method by the menstrual method of the (W, Ti) C particle powder of the present invention (Claim 1) is shown. The dimension and shape of the test piece used for the PTA overlay test are shown. (A)-(f) shows the build-up sectional drawing of the test piece used for the PTA build-up test. (A)-(f) shows the hardness of the build-up structure | tissue of the test piece used for the PTA build-up test, a matrix, and a hard particle, respectively.

Claims (2)

  Composed of composite carbide particles having W and Ti as main metal components synthesized by diffusion in a metal bath of metal and carbon, the metal components consisting of Co, Ni and Fe are suppressed to a total content of 3% by weight or less, and A binderless particle powder for surface hard wearing having an average particle size of 20 to 200 μm and having oxidation resistance, high hardness and high dispersibility.   W, Ti synthesized by diffusion of metal and carbon in a metal bath, and sub-metal component M (where M is one or more of Nb, Ta, Zr, and V metal components) Composed of composite carbide particles as components, containing a metal component consisting of Co, Ni and Fe in a total content of 3% by weight or less, and containing a secondary metal component M in a total content of 20% by weight or less, and A binderless particle powder for surface hard wearing having an average particle size of 20 to 200 μm and having oxidation resistance, high hardness and high dispersibility.

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