JPH04505478A - Composite sample source evaporation device and evaporation method for alloy production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Composite Sample Source Evaporation Apparatus and Evaporation Method for Alloy Production This invention is based on our earlier British patent G. Physical vaporization of the type described in B 1206586 and GB 1265965 An improved apparatus and method for producing alloys by a precipitation process. The above case The gold component is evaporated from one or more evaporation baths to be condensed onto a temperature-controlled collector. The device is operated under vacuum in a vacuum chamber.

The apparatus and method described herein are particularly useful for producing desired alloys in large quantities for engineering purposes. It is suitable for manufacturing. The deposit may be a sheet, strip or other can be removed from the collector for processing into a shape with the desired mechanical properties. of such thickness that it can be heat treated before, during or after processing to achieve quality , and developing sufficient structural integrity. Alternatively, the precipitated alloy is removed and then For example, if it is desired to obtain an article similar in shape to the final product, powder It can be ground for subsequent processing by metallurgical techniques.

Recently, an improved magnesium alloy made with rapid solidification rate (hereinafter referred to as R3R) has been developed. There is increasing interest in the possibilities offered by the creation of new compositions that can be achieved through manufacturing processes. It's getting bigger. Although magnesium is the lightest structural metal, its alloys did not find widespread use in aerospace applications. It's partly mechanical This is due to certain deficiencies in physical properties, but primarily due to poor corrosion resistance.

Surface protection of magnesium alloys manufactured by normal non-R3R method using other alloy systems materials such as aluminum, chromium or silicon that are known to form films. Addition of such elements is ineffective due to insufficient solubility in the magnesium matrix. . Under normal equilibrium conditions, the concentration of such additives in solid solution will be sufficient to prevent corrosion. very low to provide an effective barrier against

For the purpose of improving corrosion resistance, additives are added in solid solution with uniform electrode potential. It is very important to be assimilated.

If the additive is allowed to separate and form a precipitate, then the precipitate and when the parent bodies have different electrode potentials, the additive acts as a galvanic cell. Functioning effectively, corrosion resistance is made worse rather than improved.

Rapid solidification and physical vapor deposition techniques overcome thermodynamic constraints and allow component atoms to , before having the opportunity to move, as in the normal melt-chill process. At that location, the ingot metal is frozen by freezing J (Ir+e+ing) of the component atoms. It provides a means to achieve compositions that go beyond the scope of science. Therefore, these techniques Increasing the population of corrosion-inhibiting species in the magnesium matrix without the formation of harmful precipitates A potential solution for improving corrosion resistance in magnesium alloys by I will provide a.

Physical vapor deposition has several advantages over R3R processing.

First, the cooling rate is higher, thus improving the chance of forming a solid solution. No. Second, the selection of the possibility of alloying the components is such that some elements are , are immiscible in the molten state, whereas the above of the elements can be directly mixed. , greatly expanded. magnetization at the melting temperature of many potentially interesting alloying additives. The above is true because sium has a very high vapor pressure and will evaporate quickly. This is especially true in the case of magnesium.

containing e.g. aluminium, chromium or silicon by a physical vapor phase deposition process The production of magnesium alloys requires a large gap between the vapor pressure of magnesium and the vapor pressure of additives. Providing special issues for the difference. The above-mentioned patent specification states that the alloy component is a single evaporator. It is disclosed that it can be evaporated either from a generator or from a separate evaporator. Simple Whenever possible, both for the sake of It is desirable to use one evaporator. However, if the alloying components, e.g. As in the magnesium-chromium system, it has several orders of magnitude different vapor pressures. This is no longer practical.

When the sample sources to be separated are arranged side by side, the composition of the precipitate is Not uniform across the substrate due to total mixing. Better mixing allows for better mixing from the sample source. This can be achieved by increasing the collector separation, but this reduces the precipitation rate. It has a depressing effect.

One way to approach this problem is to introduce lateral movement between the relative positions of the collector and sample source. It is to introduce. In practice, the sample source remains stationary while the collector rotates or reciprocates. It is easy to move by any of the exercises. Different parts of the substrate in this way exposure to each sample source is equal. Movable collector helps improve precipitate homogeneity While offering significant improvements, it is possible to analyze A small amount of local non-uniformity still occurs in order for the output to be effectively constructed. There is. In structural materials, even this level of non-uniformity can be limiting to its overall strength. Possibly, it would also be inappropriate for corrosion resistance.

Until now, gas phase deposition from composite sample sources has been a compromise between precipitate homogeneity and deposition rate. or require special equipment resulting in movement of the substrate relative to the position of the sample source. It was either that. The latter choice is due to the need to maintain the equipment under vacuum. It's getting complicated.

Even when the constituent elements have widely different vapor pressures, high It is an object of the present invention to provide an apparatus and method for promoting the precipitation of homogeneous alloys at high speeds. It is a purpose.

The present invention is a method for vaporizing alloy components under vacuum and condensing the component vapors onto a collector. This is a device for producing alloys according to the process. A conduit establishing a rising flue with an outlet at its upper end, above the rising flue a collector arranged to collect steam flowing out from the outlet; Discharge into the rising flue at a position away from the discharge opening of the rising flue. a first evaporation crucible positioned and arranged to positioned within said rising flue, intermediate said outlet and said first evaporation crucible; the second evaporation crucible, with no obstructions to the flue passage around it. the second evaporation crucible arranged and arranged; a first heating means for heating the charge in the first evaporation crucible; Controlling the temperature of something to maintain it at a desired level to generate significant vapor pressure a first heating means that can be controlled; a second evaporation crucible; a second heating means for heating the charge in the second evaporation crucible, the charge Controlling the temperature of something to maintain it at a desired level to generate significant vapor pressure a second heating means that can be controlled; and Suppresses the condensation of steam on the walls of the conduit, thereby promoting mixing of the respective steam flows. At least in the upper part of the wall of the second evaporation crucible, in order to wall heating means for heating said conduit to a temperature at least higher than the temperature of the hot evaporation crucible; It includes.

From another point of view, the present invention evaporates the alloying components under vacuum and deposits the components on the collector. Provides a method for producing an alloy by a process of condensing steam, the method comprising: the first alloying component or a relatively high volatility first alloying component charge; from an evaporation crucible by heating it to a temperature sufficient to generate a vapor pressure of evaporation, loading of other alloying components or other alloying components of relatively low volatility. The first step is to heat something to a temperature sufficient to generate significant vapor pressure. Evaporating from two evaporation crucibles, a flow of component vapor from each evaporation crucible maintaining this by continuous heating of the charge; in a rising flue established with a conduit containing at least a second evaporation crucible; to direct the component vapor flow and to suppress condensation of the vapor on the walls of the conduit; at least in the portion of the wall of the conduit above the second evaporation crucible; heating the walls of the steam conduit to a temperature at least higher than the temperature of the crucible; mixing the respective vapor streams at a portion of the conduit wall above the second crucible; and Mixed steam to impinge on the collector located above the rising flue. This includes discharging from the rising flue.

Obviously, for successful operation of the present invention, the walls of the container must be exposed to the metal vapors with which they come into contact. It should be formed from an inert material.

The choice of material will therefore be determined by the nature of the metal to be evaporated.

The dimensions of the conduit are designed to allow sufficient diffusion to evaporate from the hot walls of the conduit to promote mixing. It should appear to be generated by the reflection of gas atoms. If the conduits are connected to each sample source If it is too large relative to its size and the rate of vapor flow from it, the sufficient mixing cannot occur because the separation distance is too large for sufficient diffusion to occur. do not have.

Conveniently, the components evaporated from the first or lowermost evaporation crucible are the most volatile. , is also a major alloying component. Unwanted condensation of steam on undesired parts of the equipment and Difficulties arising from backflow of steam flow into the cooling zone are due to temperature gradients in the rising flue. by maintaining the temperature by independent control of the first and second heating means. easily becomes the minimum. As a result, the second evaporation crucible has a higher temperature than the first evaporation crucible. experience.

Conveniently, the flue is assembled from a number of longitudinal sections.

This allows easier access to a particular or each evaporation crucible in the flue passage. This not only simplifies the assembly of the device between each operation, but also promote the use of different substances. For example, the lowest part of the device is the hottest part of the device. from the insulation to minimize heat transfer downwards from the deep zone to the evaporation crucible below. can be formed. This is a sample of a substance whose bottom evaporator is partially volatile. This is particularly important when containing sources.

Why do evaporative sample sources require passageways or nozzles to direct their vapor streams into a normal mixing chamber? The inventors have not given any theoretical reason why they could not be placed side by side using an arrangement of screws. I don't know, but practical considerations support vertical placement. Firstly, general The direction of vapor flow is naturally determined by the nature of the fact that the vapor originates from a molten bath. It is above average. Diverting the flow from this general upward path is heated to a temperature at least as high as the hottest evaporation crucible for reasons of requires the intervention of guiding means, which may need to be In this way external energy is spent keeping additional components hot. Second, vertical placement is the most compact. Therefore, it can be housed in a smaller vacuum chamber.

Another advantage of the present invention compared to known physical vapor deposition devices is that undesirable Precipitate alloys without relying on slow precipitation or collector deformation across the precipitation field. has a more homogeneous composition across the substrate. Equipment is homogeneous alloy It has the potential to produce several millimeters per hour or at a slightly higher deposition rate.

The disadvantage of using very high deposition rates is that an unacceptable degree of porous structure is produced in the product. , and therefore the speed in practice is Optimized.

Careful limitation of the above flow rates from each evaporator allows for a large number of configurations with wide differences. can be precipitated between their vapor pressures.

The invention will now be described by way of example with reference to the drawings.

FIG. 1 is a schematic diagram of the device; Figure 2 shows the preferred shape of the device, with some details removed for clarity from the right-hand side. FIG.

Referring now to FIG. 1, reference number 1 indicates the lower evaporation sample source located at the bottom of the flue 4 , in which a second evaporative sample source 2 is arranged in the steam flue. flue 4 Opposite the mouth is a collector 5 which receives the mixed vapor emanating from the flue. sample Each of sources 1 and 2 has an associated heater 6.7. Lower heater 6 act directly to heat the wall of the crucible containing the lower evaporative sample source 1, and the other On the other hand, the second heater 7 heats the wall of the flue which in turn radiates heat to the second vaporized sample source 2. act in order to The steam is thus exposed to the sample source, where the flue wall is at least the hottest. The heat generated from the second sample source satisfies the conditions of being as hot as Ru.

Steam from sample source 1 is supplied to flue 4, passes through sample source 2, and is combined with the vapor from sample source 2. It flows into a mixing zone 8 where it is mixed. The mixed zone is simply a sample where both types of vapor coexist. This is the part of the flue above source 2. Between the steam stream 1 and the flue wall or the second sample source 2 The collisions act to randomize the motion of the vapor atoms, which is caused by the Helps mix with steam.

Similarly, collisions between the vapor stream from sample source 2 and the flue wall cause the vapor atoms to Promote essential mixing by conveying movement. Mixed steam generated from the flue opening The airflow is therefore homogeneous in nature and precipitates with a homogeneous microstructure are collected. 5.

Figure 2 shows the device in vertical section with some details removed for clarity from the right-hand side. A preferred shape is shown. The arrangement depicted here is particularly suitable for aluminum, for the precipitation of magnesium alloyed with low vapor pressure components such as aluminum or silicon. uttered.

The lower evaporator encloses a mild steel crucible 10 mounted on an alumina support ring 11. The steam support ring minimizes the conduction of heat escaping from the crucible to the support base 12. It acts to make it smaller. The crucible is a mild steel gasket 30 and a screen It is sealed with a plid (1e+ew-Ioplid) 31. The above lid and gas A graphite nozzle 32 is placed in the center of the sket assembly. The aim is to control the flow of magnesium vapor from the crucible.

The nozzle, gasket and crucible lid described above vaporize certain elements from the crucible below. These are any features that may be necessary to make it emit. For example, the initial Experience has shown the presence of an oxide layer on the molten metal surface that prevents metal evaporation. oxide When present, the evaporation rate was unacceptably low. raising the temperature , the oxide diffuses around the crucible leaving a clean pool of molten metal in the center of the crucible. It has little effect until you reach the point where you do it. At that temperature the evaporation rate was very high . The lower evaporator is operated at a temperature high enough to remove oxides from the magnesium surface. and insert the nozzle into the mouth of the sample source to reduce the flow rate to the desired level. The above difficulties were eventually overcome. Required evaporation for magnesium The temperature ranges from 700 to 800°C.

The support platform 12 provides a positive engagement for the support ring 11 and the lower heater support 15. Recesses (+3 and 14) are provided in each to provide a fit. downward The heater support 15 has a slot 16 through which the fibrous heater element 17 passes. It is an alumina tube. The heater element 17 is wound in a spiral shape around the lower crucible 10. Contains single bare wires of raised tantalum metal. The above to reduce radiation loss The heater is surrounded by three stainless steel screens 1B.

A molybdenum disk 19 is discharged from the top heater 27 to the lower part of the mild steel crucible 10. placed above the crucible and screen to reduce the amount of heat generated.

After passing through the nozzle 32, the above is actually a vertical smoke formed on one part of the earthwork. Enter road 40. The bottom part 41 is made of alumina, which has poor thermal conductivity. As a result of isolating the first evaporative sample source from the high temperatures that are typical for the second evaporative sample source. It is useful for The central portion 42 and the top portion 43 are Made from graphite.

The crucible 20 holding the second vaporized sample source is located at the central portion 42 and the top portion of the flue 40. 43. It is graphite support ring 21. This support ring passes through the crucible 20 from the sample source below. Has numerous holes to facilitate the passage of magnesium above into the top part of the flue There is. The top portion of the flue establishes a mixing zone 44. Here, the sample source below steam from the second sample source flows away from the flue and into a temperature-controlled chamber. Mix before condensing onto the rector 50.

Different materials may be employed for the crucible 20 depending on the material to be evaporated. Aluminum The crucible is suitable for evaporating alumina or chromium, whereas vitreous carbon The vase is used for evaporating silicon.

A second radiant heater 27 is used to heat the flue adjacent to the second vaporized sample source. be done. The heat emanating from the flue then in turn evaporates the second evaporative sample source from which it evaporates. Used for heating to generate Qi. Successful operation of the invention will result in smoke Make sure the temperature of the pipe is at least as high as the temperature of the second evaporator - otherwise the steam will smoke. By keeping the soil condensed on the road wall. A radiant heat source radiates heat onto the crucible 20 The arrangement schematically shown in this drawing, such as that used to heat a flue, By doing so, the steam difficulties are eventually overcome.

The reason for choosing graphite as the material for the middle and top part of the flue is that Firstly, graphite has high thermal conductivity and high emissivity. This means that heat is transferred by radiation to the inner wall of the flue and from there to the crucible 20. Allow rapid movement. Second, graphite is physically and chemically under vacuum It is stable up to 3000°C and can be easily machined for molding.

The upper heater 27 is also mounted through a slot 26 in the tubular alumina heater support 25. It is a single bare tantalum wire wound into a spiral shape. These upper heater supports The lower It is paired with the other 15. The plug 24 fits loosely into the lumen of the alumina tube. It is shaped like this.

The operating temperature of the second evaporator will obviously depend on the material being evaporated. for example , aluminum and chromium at 13 [1tl’C to achieve sufficient evaporation rate. , while silicon requires a temperature of about 1550°C. higher temperature At this temperature, tantalum was susceptible to chemical interactions with the supporting material. degrees indicate the highest practicable operating temperature of the apparatus as described.

The operating temperature range is expanded by using exciting combinations of heaters and support materials. It can be done.

The flue has a much higher temperature in operation than the mild steel crucible 10, so it releases more radiation. A radiation screen is provided to surround the crucible and provide the necessary The screen relies on the evaporation temperature of the second sample source. The three innermost scripts Molybdenum is made from molybdenum, which does not melt up to 2610℃ and has a very low vapor pressure. There is.

The remaining screens are made of stainless steel with no risk of precipitate contamination. protected from heat sources and should be cooled for minutes.

Finally, five horizontally arranged annular molybdenum screens 29 Cover the collector 50 with a copy of the excessive convergence correction form (translation) submission form (Patent Shibucha Article 184-8) V October 21, 1991

Claims (8)

[Claims] 1. The process involves vaporizing the alloying components under vacuum and condensing the component vapors onto a collector. equipment for the production of alloys with A conduit establishing a passageway to collect the vapor escaping from the outlet of the rising flue. collectors placed in Discharge into the rising flue at a position away from the discharge opening of the rising flue. a first evaporation crucible positioned and arranged to positioned within said rising flue, intermediate said outlet and said first evaporation crucible; the second evaporation crucible, with no obstructions to the flue passage around it. the second evaporation crucible arranged and arranged; a first heating means for heating the charge in the first evaporation crucible; Controlling the temperature of something to maintain it at a desired level to generate significant vapor pressure a first heating means that can be controlled; a second evaporation crucible; a second heating means for heating the charge in the second evaporation crucible, the charge Controlling the temperature of something to maintain it at a desired level to generate significant vapor pressure a second heating means that can be controlled; and Reduces condensation of steam on the walls of the conduit, thereby promoting mixing of the respective steam streams. At least in the upper part of the wall of the second evaporation crucible, in order to wall heating means for heating said conduit to a temperature at least higher than the temperature of the hot evaporation crucible; A device that includes 2. The wall heating means described above may cause a second heating by producing radiation from the walls of the conduit. Claim 1, characterized in that it also serves to heat the evaporation crucible of Device. 3. The first heating means described above maintains a significant vapor pressure of the most volatile component(s). the second heating means is controllable to produce a significant amount of vaporization of the other component(s); The first and second heating means are controllable to maintain the atmospheric pressure, and the first and second heating means Maintain a temperature gradient in the rising flue that promotes flow toward the outlet. 3. A device according to claim 1, characterized in that it is controllable in order to 4. The flue is assembled from vertical sections, the lowest section of which is connected to the device. from the insulation to minimize heat transfer from the hottest area of the 4. The device according to claim 3, characterized in that the device is made of: 5. the flow rate of the vapor generated from said evaporation crucible containing the most volatile component; Claims 1 to 4 have a nozzle for controlling the A device according to any one of the above. 6. The process of vaporizing the alloying components under vacuum and condensing the component vapors onto the collector A method for physical vapor phase precipitation of a metal alloy, the method comprising: the first alloying component or a relatively high volatility first alloying component charge; the first evaporation crucible by heating it to a temperature sufficient to generate a vapor pressure of evaporation from other alloying components or loading of other alloying components of relatively low volatility. A second process is carried out by heating the filling to a temperature sufficient to generate significant vapor pressure. evaporating from the evaporating crucibles, the flow of component vapors from each evaporating crucible maintained by continuous heating of the charge; in a rising flue established with a conduit containing at least a second evaporation crucible; to direct said component vapor flow and to inhibit condensation of vapor on the walls of said conduit; at least in the portion of the wall of the conduit above the second evaporation crucible; heating the walls of the conduit to a temperature at least higher than the temperature of the crucible; mixing the respective vapor streams at a portion of the conduit wall above the second crucible; and Mixed steam to impinge on the collector located above the rising flue. emitting from the rising flue. 7. The charge in the second evaporation crucible is exposed to beam radiation from the heated wall of the conduit. 7. The method of claim 6, comprising heating indirectly by radiation. 8. The components are evaporated from an evaporation crucible placed above another evaporation crucible; so that the second evaporation crucible experiences a higher temperature than the first evaporation crucible. and the vapor flow towards the collector by controlling the temperature of the second evaporation crucible. This includes maintaining a temperature gradient inside the flue to promote 8. The method according to claims 6 and 7.