JPH0440313B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing a novel ceramic-metal composite material (hereinafter sometimes simply referred to as ceramic material). The present invention is related to the invention described in Japanese Patent Application No. 60-52170 (see Japanese Unexamined Patent Publication No. 61-6173) filed by the same applicant. The ceramic material obtained by this invention has a dense polycrystalline microstructure. It is particularly strong and has greater fracture resistance than ordinary ceramics. (Background of the Invention) The method of this invention is a method of making ceramic material, and has been made based on the following discovery. That is, as stated in the above-mentioned referenced patent application, between a metal or metal alloy (hereinafter referred to as parent metal) and its oxidation reaction product, which normally forms a passive coating in the presence of a vapor phase oxidizing agent. When there is essentially no suitable surface energy relationship for shows. These surface energy relationships then result in a favorable wetting phenomenon in which the parent metal is transferred through the reaction product. Prior to this discovery, where such a unique surface energy relationship did not inherently exist between the parent metal and its oxidation reaction products, it was possible to achieve effective results only by alloying the dopant with the parent metal. It was thought that it could be replaced with However, according to the surprising discovery of the present inventors, such a surface energy relationship can be induced by simply providing one or more dopants on the surface of the parent metal without alloying with the parent metal. As described in the above cited patent application, local metal migration and ceramic growth phenomena occur on the selectively doped parent metal surface. This discovery suggests that ceramic growth does not occur arbitrarily on the parent metal surface, but rather
This has the advantage that it can be used more effectively, for example, for the growth of ceramic materials (by doping only one side of the parent metal plate). Also, for commercially available metals or alloys that cannot otherwise have properly doped compositions, the present invention allows these metals and alloys to be grown in the parent metal without alloying. There is an advantage that it can be done. In this invention, the parent metal is selectively doped by using one or more layers of dopants on all or part of its surface. Such a layer can be formed by coating, dipping, silk screening, vapor deposition, sputtering, etc., and can contain an organic or inert inorganic binder solvent, a binder, etc. The doped parent metal is then placed in an oxidizing atmosphere at a temperature higher than its melting point. Under this process, the liquid parent metal oxidizes from its outer surface and advances toward the oxidizing atmosphere. In this case, the oxidation proceeds along grooves, grooves formed in the plane of the high-energy grain boundaries in the otherwise impermeable reaction product structure. New materials are continually formed by the reaction of liquid metals with vapor phase oxidants, resulting in the growth of ceramic structures that are the reaction products of metals and vapor phase oxidants, initially
interconnected along low energy grain boundaries. The resulting material also contains some or all of the parent metals or alloying components, which metals are distributed in metallic form throughout the microstructure in interconnected or insulated form. These can be made larger or smaller depending on the processing conditions described in detail below.
If the metal material is uniformly dispersed and the reaction product or metal structure is dense, the resulting ceramic will have high fracture toughness and strength. The materials of this invention can be grown to thicknesses that are substantially uniform across their cross-sections, which is not possible with conventional methods for obtaining dense ceramic structures. The method for obtaining these materials also does not require fine powder and pressing as in conventional methods, avoiding increased costs. Ceramics have recently been considered as an alternative to structural materials previously made of metal. The reason why ceramics are being replaced in this way is because ceramics have superior properties compared to metals, such as corrosion resistance, hardness, elastic modulus, and fire-resistant capacity, and ceramics can generally obtain these properties. This has led to the fact that applications are opening up for many components and systems that were previously restricted. Future areas of use include engine parts, heat exchangers, cutting equipment, bearings and wear surfaces, pumps and marine equipment. However, the use of ceramics in place of metals for such structural components requires improving the strength and fracture toughness of ceramics to reduce cost and improve reliability under specified conditions such as tensile loading, vibration, and shock. It is necessary to increase it. To date, efforts have been made to create high strength, reliable monolithic ceramics, which have been the focus of improvements in powder technology.
Although technological improvements have been made in the properties of ceramics, they are complex and generally not cost effective. The following two points can be emphasized in the conventional powder technology. 1. Improvements in methods for producing ultra-fine and uniform powders using sol-gel, plasma and laser techniques. 2. Densification and compaction technology using superior sintering, hot press, high temperature hydraulic press, etc. Such efforts result in dense, microcrystalline,
With the aim of obtaining a fluid microstructure, such a method in fact creates the possibility of structural use in ceramics. However, in the conventional technique, when trying to obtain ceramics of industrially usable quality, the cost of ceramics increases significantly. There are other unresolved issues in ceramic material technology. This means that modern ceramic processing results in dimensional changes. Conventional techniques for densification (e.g. removal of voids between powder particles) are difficult to apply to large, monolithic components of ceramics, such as single crystal liners, pressure shells, boilers and superheating tubes. . Processing time and compaction force problems increase dramatically as part size increases. The thickness of the pressure chamber walls used for processing (for high-temperature hydraulic presses) and the die size (for hot presses) increase geometrically with increasing size of all ceramic products. The invention described herein seeks to provide a method for producing dense, high-strength, and fracture-resistant ceramic microstructures with a simpler mechanism and at lower cost than conventional methods. With this invention, large or thick ceramics can be made reliably, and new expectations can be held for ceramic materials that could not be expected with conventional techniques. Previously, oxidation of metals was considered an attractive method for forming oxide-type ceramics. As used in this specification and in the claims, the term "oxidation reaction product" means any oxidation state of the metal. Here, the metal can release electrons to other elements or combinations of elements to form compounds and, for example, bind metal compounds to oxygen, nitrogen, halogens, carbon, boron, selenium, tellurium and combinations thereof. try to cover it. The method of forming the ceramic material of this invention is fundamentally based on the discovery of certain conditions that can create the surprising oxidation behavior of metals. In order to properly appreciate the significance of this discovery, it is important to understand how the oxidation behavior of metals was generally understood and how metal oxidation was traditionally used as a mechanism for making ceramics. It would be useful to know how it was used. The term "oxidizing agent" used in this specification corresponds to the definition of "oxidation reaction product" above, and is broadly defined as an oxidizing agent, that is, a compound that performs a redox reaction on a metal, depriving the metal of electrons. means a compound. There are classically four general modes of metal oxidation. First, certain metals oxidize when exposed to an oxidizing atmosphere, forming oxidizing reaction products (flake-like, crushed or porous), so that the metal surface is constantly exposed to the oxidizing atmosphere. In such processes, when the metal is oxidized, no independent objects are formed, but frames or particles are formed. For example, iron oxidizes and reacts with oxygen in such a way. Second, some metals (e.g. aluminum, magnesium, chromium, nickel, etc.) are relatively thin;
Forms a protective oxidation reaction film and oxidizes. This coating transports the oxidizing agent or metal at a low rate, so that the underlying metal is effectively protected from further oxidation. Third, other metals are known to produce solid or liquid oxidation product films that do not protect the underlying metal. This is because such reaction products are capable of transporting oxidants. Even though the oxygen permeable film inhibits the rate of oxidation of the underlying metal, not all of the metal itself is protected by the film due to its oxidant permeability. This latter type of oxidation involves, for example, exposing silicon to hot air to form a glassy film of silicon oxide, which is permeable to oxygen. Generally these processes do not occur nearly fast enough to create a useful thickness of ceramic material. Finally, other metals are known to form oxidation reaction products under certain conditions. These volatilize and continually expose new metal to oxidation. For example, tungsten reacts with oxygen at high temperatures and oxidizes in this way to form _WO3 . Both of these classical oxidation modes are unlikely for the formation of ceramic materials for the reasons discussed above. However, as a variation of the second mode described above, a flux is applied to the metal surface to dissolve or destroy the oxidation reaction products, allowing for the migration of the oxidant or metal, resulting in a thicker oxidation reaction product than would be possible naturally. A film can be created. However, this technology is limited to creating independent ceramic structures with relatively low strength and thin walls. Such techniques are used to mix metal powders with other particles and oxidize the surface to obtain unique porous low strength ceramics. Examples include US Patent No. 3255027 (H. Tarsma) and US Patent No. 3299002 (WA Hull). Similar methods have also been used to make thin-walled Al ₂ O ₃ refractory structures. For example, US Patent No. 3473938 (RE Oberlin) or Thin Wall Hollow Refractory Particles (US Patent No.
See 3298842 (LE Sufelt).
However, these methods are limited in the thickness of the oxidation reaction product formed. This is because the effects of flux agents last only for a relatively short period of time.
After the oxidation reaction product has grown a certain amount, it reverts to the protective properties of low growth. Increasing the flux concentration promotes the growth of thick ceramic coatings, but this results in a low strength, low refractory, and low hardness product, which is not the intent of this invention. The preferred technique for making freestanding ceramics by oxidation of metals is oxidation/reduction or "redox" type reactions. This occurs when one metal reduces the oxide of another metal to form a new oxide and a reduced version of the original oxide. For example, US Pat. No. 3,437,468 (LE Sufelt) and US Pat. No. 3,973,977 (LE Wilson) use this redox type reaction to make ceramic materials. A disadvantage of this redox type reaction is that it does not produce a single hard refractory ceramic phase, as described in the above patents. In other words, the products described in redox-type reactions contain multiple ceramic phases, which reduce hardness, fracture rate, and wear resistance compared to structures with only a single ceramic phase. This invention includes a special technique to promote a new oxidation phenomenon, which is different from any of the classical oxidation modes and eliminates the problems of traditional ceramic manufacturing. This invention will be explained in detail below. SUMMARY OF THE INVENTION Applicant's related U.S. application describes a novel ceramic material that creates a unique surface energy relationship between a parent metal and its oxidation reaction products. This results in a surprising oxidation behavior of the metal. When such metals are exposed to an oxidizing atmosphere at temperatures substantially above the melting point of the parent metal alloy, they oxidize outward from the surface exposed to the oxidizing atmosphere;
It advances toward the oxidizing atmosphere by moving along grain boundaries through a dense, gas-permeable structure. Thus, the ceramic material can be grown to a desired thickness, which was virtually impossible with conventional ceramic manufacturing techniques. This invention relates to products of the same genre as the ceramic materials of the related US application. This invention is basically attributable to the following discovery. That is, the surface coating of the parent metal with a dopant causes the same surprising oxidation behavior, thereby promoting the growth of the ceramic material. According to the invention, therefore, at least one layer of doping material is used on the surface of the parent metal, and the parent metal provided with the doping agent layer is heated and placed in an oxidizing atmosphere, thereby producing the new oxidation behavior described above. This makes it possible to create a self-supporting ceramic material. In accordance with the invention, (a) the parent metal is provided with at least a portion of the surface of the parent metal which normally forms a passive coating in the presence of a vapor phase oxidizing agent, and which prevents the formation of said passive coating and in the molten state. (b) in the presence of the vapor phase oxidant, the parent metal with the dopant disposed on at least a portion of its surface is heated to its melting point; Heating to a higher temperature melts the parent metal,
and (c) reacting the molten parent metal with the vapor phase oxidizing agent to produce an oxidation reaction product at that temperature; (d) at least a portion of the surface of the oxidation reaction product is contact with the vapor phase oxidant and maintain a state between the vapor phase oxidant and the molten parent metal, thereby transporting the parent metal through the oxidation reaction product to the vapor phase oxidant. A ceramic-metal composite comprising a step of allowing a new oxidation reaction product to grow on the side of the vapor phase oxidant, and (e) continuing the above reaction to obtain a ceramic-metal composite material containing the oxidation reaction product and a metal. A method of manufacturing a material is provided. The invention thus eliminates the need for alloying dopants into the parent metal prior to processing, which provides significant cost and technology advantages. In other words, the invention eliminates the need for: That is, the parent metal is first alloyed with a requisite amount of dopant to adjust the relative surface energy relationship between the molten metal and the oxidation reaction products, resulting in surprising oxidation behavior, thereby providing As with the invention described above, there is no need for the operation of growing a self-supporting ceramic structure. Since there is no step of alloying the parent metal with the dopant, the number of steps can be reduced and the cost associated with manufacturing the ceramic body can be reduced.
Additionally, as discussed in related US applications, considerably less doping agent is required to effect oxidation and growth phenomena when applied to the parent metal surface in accordance with the present invention. Furthermore, in the method of the present invention, by limiting the placement of the dopant on the surface of the parent metal, it is possible to selectively grow the ceramic structure. Therefore, according to the present invention, the growth of the ceramic material can be controlled depending on the position of the dopant on the surface of the parent metal. This invention will be described in detail below based on specific examples. (Detailed Description of Preferred Embodiments) As mentioned above, the present invention is based on the following discovery. That is, the use of at least one dopant at the desired surface of the parent metal results in oxidation behavior similar to that described in related US applications. Here, one or more dopants are required to favor the wettability of the parent metal and to ensure the oxidation reaction at the grain boundaries. In a particularly preferred embodiment of the present invention, aluminum is used as the parent metal, and the dopants provided externally at selected locations on the surface of the parent metal include a dopant as an initiator and a dopant as an accelerator. A two-component doping system is used. In the case of aluminum, the initiator and accelerator dopants are a source of magnesium and a source of Group B elements, excluding carbon, respectively. It is not necessary to use both the initiator and the accelerator on the external surface of the parent metal, so if one of the dopants is initially alloyed with the parent metal, the other dopant can be applied externally to the parent metal surface. This causes the growth of the ceramic structure. Additionally, the use of extrinsic dopants depletes certain accelerator or initiator dopants within the parent metal, resulting in optimal growth motion for the ceramic structure. In the case of aluminum, no commercially available alloy has an optimal composition for internally alloyed dopant concentration. It has been found that such alloys can be adjusted to optimal dopant concentrations by externally providing initiator or accelerator dopants, or both, to produce maximum growth kinetics. Preferably, the initiator and accelerator dopants are uniformly coated on the surface of the parent metal. Surprisingly, there is no upper or lower limit for the amount of accelerator dopant used (unless an accelerator dopant is used), but increasing the amount of accelerator dopant used will make the ceramic structure The reaction time required is reduced. For example, if silicon is used as an accelerator dopant in the form of silicon dioxide, silicon in an amount of 0.0001 gSi/g aluminum with the initiator dopant will result in the growth of ceramic structures when air or oxygen is used as the oxidizing agent. A phenomenon occurs. Unlike accelerator dopants, there appears to be a lower limit on the amount of external dopants required for growth on an undoped parent metal, but no upper limit. Therefore, in order to grow ceramic structures from aluminum-based parent metals using air as an oxidizing agent, the initiator dopant in the form of MgO must be present in an amount of at least 0.0005 g per gram of parent metal, and the surface of the parent alloy in which MgO is used must be present. It is preferable that the amount is 0.005 g/cm ² or more. When aluminum or an alloy thereof is used as the parent metal and air or oxygen is used as the oxidizing agent used in this invention, the two-component dopant is applied in an appropriate amount to at least a portion of the surface of the parent metal, and then the parent metal is Place in a crucible or other refractory container so that its surface is exposed to an oxidizing atmosphere. The parent metal is then heated internally to a temperature typically around 1000℃~
Raising the temperature to 1450°C, preferably about 1100°C to 1350°C,
The parent metal then begins to migrate through the surrounding oxide film. Because the parent metal is continuously exposed,
As the oxidation progresses, the polycrystalline oxide films become thicker, and these follow the hyperfine structure of the parent metal along all high-angle grain boundaries of the oxide structures thus formed. The oxide structure grows at a constant rate (i.e., always grows to a substantially constant thickness).
Sufficient exchange of air (or oxidant atmosphere) maintains a relatively constant amount of oxidant source within. In the case of air, it is convenient to exchange the oxidizing agent using a vent. Growth continues until at least one of the following occurs: 1 When all the parent metal is consumed 2 The oxidizing atmosphere is replaced by a non-oxidizing atmosphere,
or when the oxidizing agent runs out or becomes empty, 3 the temperature is outside the reaction temperature (e.g. 1000℃~1450℃
dopants (initiators and accelerators) are preferably used as powders on the surface of the parent metal. A particularly preferred method of applying the dopant to the parent metal surface is to spray the parent metal surface with a liquid suspension of the dopant in water or an organic binder mixture to form a tacky film and remove the doped material before treatment. To facilitate the manipulation of parent metals. The following are also surprising discoveries. That is, the source of accelerator dopant may be provided by a solid object, ie, a solid object composed primarily of accelerator dopant, bonded to a portion of the parent metal surface. For example, it has been found that a silicon-containing glass can be applied over a portion of a parent metal surface that has been previously provided with an initiator dopant. When the parent metal on which the glass is placed is placed in an oxidizing atmosphere in the temperature range of about 1000°C to 1450°C, a ceramic body grows. Examples will be explained below. In each embodiment, atmospheric pressure air supplied by convection from a ventilation hole is used as the oxidizing atmosphere. Example 1 Commercially available pure aluminum (1100 alloy) at 1100℃~
The temperature was set at 1450°C, and the effect of temperature and the effect of an oxidizing dopant containing a magnesium initiator and a silicon accelerator on the growth of the ceramic body were investigated. As samples, aluminum sheets each having a width of 2 inches, a length of 9 inches, a thickness of about 3/16 inches, and a weight of about 100 g were used. The sheets are embedded in a bed of aluminum oxide so that the exposed 9 inch side of the sheet is flush with the surface of the bed.
The exposed surface is coated with a small amount (g) of fine magnesium oxide powder and then a small amount (1 g) of silicon dioxide powder to evenly cover the desired growth surface. In each experiment, air was allowed to enter the cycle, and the experiment was conducted as follows. Time course Temperature °C 0 to 5 hours 30 to set temperature 5 to 29 hours Set temperature 29 to 34 hours Set temperature to approximately 600 34+ hours Removed from various samples by visual observation and measurement of weight increase of crucible and additives. It was investigated. "Weight increase" as used herein refers to the rate of total weight change in the refractory container, aluminum oxide bed, and ingot before and after the cycle, and is expressed in g/g. When aluminum alloy is relatively completely converted into ceramic material, the weight increase is 0.89 g/g of aluminum parent metal (corresponding to complete conversion to aluminum Al ₂ O ₃ ). If unreacted aluminum remains in the parent metal, a few percent (e.g.
15%) of the metal phase. The weight increases in the above treatments do not correct for bed or crucible moisture removal or other experimental errors, and the temperatures are shown in Table 1 below. Table 1 Set temperature Weight increase 1100℃ 0.00 1125℃ 0.00 1150℃ 0.15 1175℃ 0.57 1200℃ 0.68 1225℃ 0.46 1275℃ 0.56 1300℃ 0.44 1325℃ 0.27 1350℃ 0.34 1375 ℃ 0.13 1400℃ 0.19 1425℃ 0.14 Example 2 Surface When changing to the ceramic body of the present invention, in order to investigate the order in which magnesium oxide and silicon oxide were provided on the surface, silicon oxide was first provided, and then magnesium oxide was provided. As a result, the ceramic body and weight gain were the same as those described in Example 1, and the weight gain is shown in Table 2. Table 2 Set temperature Weight increase 1100℃ 0.00 1150℃ 0.04 1200℃ 0.55 1250℃ 0.53 1300℃ 0.39 1350℃ 0.20 Example 3 To investigate the case where the initiator and accelerator are combined, magnesium oxide and silicon oxide The mixture was mixed in a 1:1 ratio to give 2 g, which was used on the parent metal surface using the method of Example 1. Table 3 shows the weight gain in this example. Table 3 Weight increase data and set temperature when treated with a mixture of magnesium oxide and silicon oxide on the parent metal surface Set temperature Weight increase 1200℃ 0.75 1250℃ 0.53 1300℃ 0.43 Example 4 Initiator or accelerator In order to investigate the effect of processing 1100 aluminum alloy without the addition of aluminum, the samples were treated in the manner described above without any material on the exposed surfaces. the result
At a set temperature of 1100-1350°C, no growth of the desired ceramic material was observed. Example 5 It was investigated whether a ceramic body according to the present invention would grow when externally doped with a compound containing another Group B element as a magnesium initiator and an accelerator. The experiment was conducted in the same manner as in Example 1, except that a small amount (1 g) of magnesium oxide and 2.5 g of tin oxide were used on the exposed surfaces. The weight gain when using tin oxide as an accelerator dopant is shown in Section 5A. In the same way, a small amount (1 g) of magnesium oxide and then 1.7 g of germanium dioxide were applied externally. The weight increase when germanium dioxide is used as an accelerator dopant is
Shown in 5B. Table 5A Weight gain data and set temperature when tin oxide accelerator and magnesium oxide initiator are added to exposed surfaces Set temperature Weight gain 1150°C 0.02 1200°C 0.78 1225°C 0.80 1250°C 0.83 1275°C 0.81 1300°C 0.77 1350℃ 0.45 Table 5B Weight increase data and set temperature when germanium oxide accelerator and magnesium oxide initiator are added to the exposed surface Set temperature Weight increase 1200℃ 0.77 1250℃ 0.50 Example 6 Others containing magnesium In order to investigate the growth effect of ceramic when externally doped with a compound _of
2 g of O ₄ ) and 1 g of silicon dioxide were added. In this experiment, the set temperature holding time was 36 hours. Weight gain data is shown in Table 6. Table 6 Weight increase data and set temperature when magnesium aluminate spinel and silicon dioxide are added to the exposed surface Set temperature Weight increase 1100℃ 0.00 1125℃ 0.01 1175℃ 0.29 1225℃ 0.22 1275℃ 0.15 1325℃ 0.20 1375℃ 0.09 Example 7 To study the combination of dopants internally alloyed with the parent metal and externally applied dopants, aluminum alloys containing 0.5 to 10 wt% internal magnesium initiator dopants were prepared.
For magnesium alloys, silicon dioxide was used externally over a set temperature range. In each experiment, the sample was 1 inch long and 1 inch in diameter.
Cylindrical ingots of aluminum-magnesium alloy cast from molten metal at 850° C. were used. This cylindrical ingot was placed within a 90 mesh aluminum oxide refractory particle in a suitable refractory crucible. Expose the cut surface of the ingot,
It was located substantially flush with the surface of the aluminum oxide. On this surface, 0.05 g of -140 mesh powder of silicon dioxide was dispersed as an accelerator. In this case the cycle is as follows. Time course Temperature °C 0 to 4 hours 30 to set temperature 4 to 16 hours Set temperature 16 to 20 hours Set temperature to 600 20+ hours Removed from For each alloy, weight gain was determined using the method described above. The results are shown in Table 7.

【table】

【table】

[Table] Example 8 In order to obtain a large monolithic sample of the ceramic body according to the present invention, 4/9
Made of 4 boards measuring 8 inches x 0.5 inches,
Commercially available 5052 containing 2.5% Mg internal initial dopant and less than 0.2% known accelerator dopant.
A material made of aluminum alloy was used. These were wrapped in aluminum foil with less than 0.5% initiator and accelerator dopant inside, which gave them a height of 2 inches.
This was further placed within a suitable refractory particle within a refractory container. The top 8 x 9 inches are exposed;
To this exposed surface was applied 12 g of a silicon dioxide accelerator dopant dispersed in a solution of polyvinyl alcohol and water, followed by 4 g of a powdered silicon dioxide material. This is done at a set temperature of 1125℃.
Processed for 160 hours. In this case, it took 10 hours to reach the set temperature, and it took 12 hours to cool before taking it out. After treatment, the weight increase rate was approximately 0.40 compared to the original parent alloy's weight of 6500 g. The cross section of the resulting single-structure ceramic material is approximately 10 inches x
It was 9 inches by 1 inch. This is shown in FIG. EXAMPLE 9 To study the formation of ceramic bodies with local surface application of accelerator dopants, a ceramic body measuring 9 x 2 x 0.5 inches and containing 2.5% magnesium as an initiator dopant was prepared. A commercially available 5052 aluminum alloy was used and described in the method of Example 8. Approximately 2.0 silicon dioxide dispersed in polyvinyl alcohol and aqueous solution as an accelerator dopant is applied to the central 3 x 2 inches of the 9 x 2 inch exposed surface.
g was used. This sample was treated at a set temperature of 1125°C for 48 hours. In this case, it took 5 hours to reach the set temperature, and it was removed after cooling for 5 hours. The weight gain was 0.16, and the resulting ceramic body grew preferentially from the externally doped surface of the parent metal. Example 10 In order to investigate the effect of externally providing a non-powder type accelerator dopant, a commercially available aluminum alloy containing 2.5% Mg as an initiator dopant was used as a sample, and this was used in Example 9. Processed as described. 2 which is the exposed surface of the parent alloy
A solid plate of silicon dioxide accelerator dopant measuring 2 inches wide, 3 inches long, 1 mm thick, and weighing 8 grams was placed in the center of the x9 inch. This was treated at a set temperature of 1125°C for 48 hours. In this case, it took 5 hours to reach the set temperature, and it took 5 hours to cool before removing. Weight increase is 0.12
A ceramic body was growing in the doped central part of the parent metal. Example 11 In order to investigate the effect of using a large amount of silicon dioxide accelerator when forming the ceramic body of the present invention, 1% Mg as an initiator dopant and 1% Mg as an accelerator dopant were added.
Two 1-inch samples of a commercially available alloy (6061) containing 0.6% Si and measuring 2 inches x 9 inches x 1/2 inch were prepared. This was placed within a suitable refractory particle within a refractory container. This exposed 2×9
1 g of silicon dioxide accelerator dopant bonded with polyvinyl alcohol on the surface of an inch
coated. Additionally, 65 grams of powdered silica was added in a 1/4 inch layer over this surface. This was then treated by exposing it to an atmosphere. This treatment is at 1310°C for 72 hours. In this case, it will take 5 hours to reach the set temperature.
It was also removed after cooling for 10 hours. The weight gain was 0.25, indicating that high amounts of silicon dioxide accelerator dopant result in significant growth of the desired ceramic body. The microstructure of the obtained material is shown in FIG. As shown in the figure, the resulting material has a metallic phase enriched in the basic silicon. Example 12 In order to investigate the case where a small amount of external accelerator dopant is used for the growth of the ceramic body of the present invention, powdered silicon dioxide 0 to 1.0
g, with dimensions of 2 x 9 x 1/2 inches,
The method of Example 9 was carried out externally applied to a commercial alloy containing 2.5% Mg initiator dopant.
The temperature setting was 1125°C for 48 hours. In this case, it took 5 hours to reach the set temperature, and the solution was removed after being cooled for 5 hours. Without silicon dioxide accelerator on the surface, the weight gain is negligible (0.015), and when 0.025-0.5 g of oxide is applied externally as an accelerator dopant, the weight gain is 0.16-0.36. It was hot.

[Brief explanation of drawings]

FIG. 1 is a micrograph of the single crystal ceramic body obtained in Example 8. FIG. 2 is a micrograph of a local ceramic body formed in Example 9, viewed from above. FIG. 3 is a micrograph showing the fine structure of the ceramic body formed in Example 11.

Claims (1)

[Scope of Claims] 1 (a) on at least a portion of the surface of the parent metal that normally forms a passive coating in the presence of a vapor phase oxidizing agent;
(b) disposing at least one doping agent that prevents the formation of said passive coating and continues a reaction involving said parent metal and a vapor phase oxidant in the molten state; heating the parent metal with a dopant disposed in at least a portion thereof to a temperature higher than its melting point to melt the parent metal;
and (c) reacting the molten parent metal with the vapor phase oxidizing agent to produce an oxidation reaction product at that temperature; (d) at least a portion of the surface of the oxidation reaction product is contact with the vapor phase oxidant and maintain a state between the vapor phase oxidant and the molten parent metal, thereby transporting the parent metal through the oxidation reaction product to the vapor phase oxidant. A ceramic-metal composite comprising a step of allowing a new oxidation reaction product to grow on the side of the vapor phase oxidant, and (e) continuing the above reaction to obtain a ceramic-metal composite material containing the oxidation reaction product and a metal. Method of manufacturing the material. 2. The method of claim 1, wherein the parent metal comprises at least one additional dopant. 3. The method of claim 2, wherein the parent metal comprises at least two additional dopants. 4. The method according to claim 1, 2 or 3, wherein the parent metal comprises aluminum. 5. The method according to any one of claims 1 to 4, wherein the vapor phase oxidizing agent comprises at least one substance selected from air, oxygen, nitrogen, halogen, carbon, boron, and combinations thereof. . 6. The method of claim 1, wherein the parent metal comprises aluminum and the surface dopant comprises at least one dopant selected from the group of substances consisting of magnesium, silicon, tin, germanium and lead. . 7. The method according to claim 4, wherein the temperature is 1000 to 1450°C. 8. The method according to any one of claims 1 to 7, wherein the reaction is continued for a period of time until the molten parent metal is substantially consumed to produce a porous ceramic-metal composite material. 9. The method of claims 1 to 7, wherein the reaction is carried out to form metal inclusions in at least a portion of the ceramic-metal composite material. 10. The method of claim 1, wherein the at least one dopant comprises at least two dopants. 11. The method of claim 9, wherein at least some of the metal enclosures are three-dimensionally interconnected. 12. The method of claim 8, wherein at least a portion of the porous ceramic-metal composite comprises three-dimensionally interconnected pores. 13. The method of claim 2, wherein at least one additional dopant is alloyed with the parent metal. 14. Claim 3, wherein said at least two additional dopants are alloyed with said parent metal.
The method described in section. 15. The method of claim 1, wherein the parent metal comprises aluminum, the vapor phase oxidant comprises air, and the oxidation reaction product comprises alpha-alumina.