JP7359459B2 - Superheated steam degreasing and sintering equipment - Google Patents

Description

The present invention relates to a superheated steam degreasing and sintering apparatus. Specifically, the present invention relates to a superheated steam degreasing and sintering device that performs degreasing and sintering using superheated steam.

When sintering ceramic powder or metal powder to form a powder sintered body, a sintered material body containing the powder and a large amount of organic binder is formed by various methods, and then the organic binder is The powder is sintered by causing the powder to disappear and heating to a predetermined temperature.

The binder removal step in which the organic binder disappears from the sintered material molded body is often performed by heating the sintered material molded body in air to a temperature higher than the temperature at which the organic binder decomposes.

In the binder removal process, if the binder component rapidly expands or decomposes inside during the heating process of the sintered material molded body, cracks are likely to occur in the sintered material molded body from which the binder has been removed. Therefore, the binder removal process is performed with the temperature increase rate set very low.

Japanese Patent Application Publication No. 2013-193412

At the above conventional temperature increase rate, it takes 24 to 150 hours to complete the binder removal process. Therefore, a large amount of energy is required and the energy efficiency is very low. Further, the power required for the heater etc. becomes very large, and the manufacturing cost also increases.

Furthermore, even if the heating rate is reduced, if the binder exceeds the required temperature, rapid decomposition of the binder component may occur inside the sintered material compact, often resulting in cracks and cracks. .

Furthermore, since the binder removal process and the sintering process are performed by heating the entire area inside the furnace using a heater or the like, highly accurate temperature control is extremely difficult.

Moreover, in a thick sintered material molded body, defects such as cracks often occur during the binder removal process and sintering process. For this reason, there are significant restrictions on the dimensions and shape of the molded sintered material that can be molded.

Furthermore, the sintering step performed after the binder removal step described above also requires a large amount of time, and since the sintering temperature is higher than the binder removal temperature, the required energy is also increased. Moreover, it is difficult to control the sintering time and temperature with high accuracy depending on the shape and the like.

The present invention solves the above-mentioned conventional problems, allows the debinding process and the sintering process to be performed in a short time, reduces the occurrence of cracks and cracks, and moreover produces a powder sintered body with high precision. It is an object of the present invention to provide a superheated steam degreasing and sintering apparatus for powder sintered bodies that can be formed.

The present invention involves degreasing a sintered material molded body formed into a predetermined shape from a molding material containing a sinterable sintered powder and an organic binder by applying superheated steam, and sintering it at a predetermined temperature. The superheated steam degreasing and sintering apparatus includes a furnace body that accommodates a sintered material compact, a superheated steam generator that supplies superheated steam to the furnace body, and a superheated steam generator that injects superheated steam from above into the furnace body. It is configured to include an injection nozzle for supplying the fuel, and an outlet for discharging superheated steam containing components obtained by decomposing the binder from the furnace body, and causes the superheated steam to flow toward the surface of the sintered material molded body. It is configured to include a plurality of the injection nozzles and a holding member that can hold the sintered material molded body and apply superheated steam to the entire periphery including the lower surface of the sintered material molded body.

Superheated steam is H ₂ O gas obtained by heating saturated steam evaporated at 100° C. to a higher temperature at normal pressure. Superheated steam can cause convection heat, condensation heat, and radiant heat to act on the heating target. Moreover, since the specific heat is about twice that of air, the heating efficiency is extremely high.

Furthermore, organic matter can be reduced to a lower molecular weight and gasified by hydrolysis using the moisture and heat of superheated steam. Furthermore, the decomposition initiation temperature is lower than when decomposition is caused by temperature alone or in an oxygen atmosphere. In addition, by controlling the superheated steam temperature with high precision, rapid decomposition such as oxidative decomposition in air can be suppressed, and the decomposition rate is fast and the decomposition efficiency is high.

In addition, the binder removal process and sintering process using superheated steam do not involve heating the entire furnace for binder removal and sintering with a heater, as in the past, but instead generate superheated steam at the required temperature. It is carried out by making it flow in a furnace and acting on the surface of the object. Therefore, not only the temperature of the superheated steam can be controlled with high precision, but also the temperature acting on the molded product in each step can be managed with high precision.

In the present invention, superheated steam that is controlled at a constant temperature that does not rapidly decompose the binder component can be made to flow toward the surface of the object and to be allowed to act continuously. Therefore, the binder is gradually disappeared from the surface of the sintered material molded body, and the binder component inside is not rapidly expanded or decomposed. Therefore, the occurrence of cracks and the like can be effectively prevented.

Moreover, the present invention includes a plurality of the injection nozzles that cause the superheated steam to flow toward the surface of the sintered material compact. Degreasing and sintering using superheated steam does not depend only on the temperature environment inside the furnace as in the past, but as mentioned above, convection heat, condensation heat, and radiant heat are applied simultaneously to the heated object. The effect varies greatly depending on the flow behavior of the superheated steam acting on the surface of the sintered material molded body and the state of the superheated steam. On the other hand, the state of the heated steam changes while flowing over the surface of the sintered material molded body. By providing a plurality of the above injection nozzles, it becomes possible to equalize the state of the superheated steam acting on the surface of the sintered material molded body. In addition, the holding member makes it possible to apply superheated steam to the entire periphery of the sintered material molded body, including the bottom surface, which not only improves energy efficiency, but also prevents defective products during the degreasing and sintering process. can be prevented. Furthermore, since the entire furnace is not kept at a constant temperature, energy efficiency is significantly higher. Therefore, it is possible to save on electricity costs such as heaters and the like, and it is also possible to reduce manufacturing costs.

The binder removal step includes a first binder removal step in which superheated steam at a temperature at which some of the constituent components of the organic binder decomposes is applied for a predetermined period of time, and a temperature at which all of the organic binder is decomposed. It is preferable to include a second binder removal step performed by applying superheated steam at a temperature above.

The temperature of superheated steam can be controlled with very high precision. Therefore, it becomes possible to apply superheated steam at a temperature at which some of the constituent components of the organic binder decompose for a predetermined period of time. Furthermore, by applying superheated steam at a constant temperature that does not cause rapid decomposition of the organic binder components, it is possible to prevent the binder components inside the organic binder from rapidly expanding or decomposing.

The first binder removal step involves applying superheated steam at a temperature 1 to 10°C higher, preferably 1 to 5°C higher than the temperature at which some of the constituent components of the organic binder start decomposing, for a predetermined period of time. It is preferable to do so. This effectively prevents the components of the organic binder from decomposing rapidly. The temperature at which some of the components of the organic binder start decomposing can be obtained by decomposing each component of the organic binder in superheated steam .

The superheated steam can be applied to the surface of the sintered material compact, and the heat capacity of the superheated steam is much larger than that of air or the like. Therefore, decomposition of the resin can be started at a lower temperature than the temperature in the conventional binder removal process performed in air. Moreover, since the above temperature is lower than the decomposition temperature due to heat and the superheated steam can act on the surface of the sintered material molded body, the binder starts to disappear one by one from the surface of the sintered material molded body. Therefore, even if the temperature inside the sintered material molded body is set lower than the decomposition temperature when using air or the decomposition temperature using inert gas, it is possible to shorten the required time, and the sintered material It becomes possible to suppress rapid expansion and decomposition of the binder inside the molded body. Thereby, the occurrence of cracks etc. can be effectively prevented.

By performing the first binder removal step, a required proportion of the binder components is eliminated. As a result, the inside of the sintered material molded body becomes porous. Thereafter, a second binder removal step is performed in which the temperature of the superheated steam is raised to a temperature that can completely eliminate the organic binder.

The organic binder is configured to include a binder component that disappears at a low temperature and a binder component that disappears at a high temperature, and disappears at the high temperature above a temperature at which the binder component that disappears at a low temperature starts to disappear. A first debinding step in which superheated steam at a temperature lower than the temperature at which the binder component starts to disappear is applied for a predetermined time, and a second step in which superheated steam at a temperature higher than the temperature at which the binder component disappears at the high temperature is applied. It is preferable to perform a binder removal step including the binder removal step 2. For example, olefin resins (polyethylene, polypropylene), polystyrene, etc. are suitable as binder components that disappear at high temperatures. On the other hand, it is preferable to use paraffin wax, polyethylene wax, polypropylene wax, fatty acid ester, phthalic acid ester, etc. as the binder component that disappears at low temperatures.

By adopting this configuration, it is possible to first eliminate the binder component that disappears at low temperatures to make the sintered material molded body porous, and then to eliminate the binder component that disappears at high temperatures. . Therefore, the time required for removing the binder can be shortened, and the occurrence of cracks and the like can be more effectively prevented.

The sintering step can be performed by raising the temperature of the superheated steam to a temperature higher than the sintering temperature of the powder, following the binder removal step. Thereby, the degreasing binder process and the sintering process can be performed continuously in the same furnace.

Alternatively, the sintering process may be carried out without using the superheated steam, and the sintered material compact after the binder removal process may be carried out in one or more of an inert gas atmosphere, a reducing atmosphere, or a vacuum atmosphere. Sintering can also be carried out.

Further, the binder removal step can be performed at a maximum temperature of 800° C. or lower by flowing a mixed gas of an inert gas atmosphere such as nitrogen or argon gas and superheated steam. As a result, when metal powder is used, it is possible to prevent the metal powder from being oxidized by the oxygen component in the superheated steam.

In the above-mentioned forming step, a sintered material molded body including at least two or more layers or parts containing organic binders having different vanishing start temperatures and/or vanishing completion temperatures is formed, and among the two or more layers or parts, the The organic binder contained in a predetermined layer or portion containing a binder with a low disappearance start temperature and/or low disappearance completion temperature can be preferentially eliminated.

As described above, the binder removal process is performed by applying superheated steam whose temperature is precisely controlled to the surface of the sintered material molded body. Therefore, the organic binder gradually disappears from the surface of the sintered material molded body, but when the binder disappears, the sintered material molded body contracts by a predetermined amount. Therefore, depending on the form of the sintered material molded body, cracks or deformation may occur due to the above shrinkage. In the present invention, it is possible to preferentially eliminate the binder in a predetermined portion of the sintered material molded body, and to control the rate of disappearance of the binder. This makes it possible to relieve stress during shrinkage and prevent cracks, etc., increasing the degree of freedom in the shape of the sintered material molded body. In addition, conventionally, the debinding process was performed according to the temperature conditions and temperature rise conditions for debinding thin parts, but since this is no longer necessary, it is expected to have the effect of shortening the time required for the debinding process. can. Further, deformation can be prevented by preferentially removing the binder from the portion where the deformation becomes large.

Furthermore, a binder removal regulating portion for regulating binder removal can be provided at a predetermined portion of the sintered material molded body during the molding step or before the binder removal step after the molding step.

By providing the binder removal regulating section, when superheated steam at a predetermined temperature is applied, it becomes possible to delay the disappearance of the organic binder in a required part or to preferentially eliminate the organic binder in a predetermined part. . For this reason, it becomes possible to relieve the stress caused by shrinkage in the binder removal process and obtain a molded article with an unprecedented form.

The binder removal regulating portion can be formed by various methods. For example, a resin layer with a high vanishing temperature can be formed on the surface of a predetermined portion of a sintered material molded body. The resin layer can be formed, for example, by integrally molding in the molding step, or by applying the resin to the surface after the molding step is completed.

Furthermore, when forming a sintered material molded body having a small thickness, the heat of the flowing molding material is rapidly absorbed by a mold, etc., resulting in a decrease in temperature and often a decrease in fluidity. In such a case, molding can be performed using a sacrificial mold made of resin or the like. That is, it includes a sacrificial mold part forming step of forming a sacrificial mold part in which part or all of the sintered material molded body can be molded in the mold, and the mold including the sacrificial mold part is filled with the molding material. The above-mentioned molding step is performed, and the sacrificial mold section can be configured to disappear or be separated in the binder removal step, the sintering step, or the subsequent sacrificial mold section removal step.

The sacrificial mold part is formed using a resin material with low thermal conductivity and high heat retention. Therefore, the heat of the molding material flowing inside the mold is difficult to be removed, and the molding material can be filled into every corner of the mold. Moreover, since the sintered material molded body can be released from the mold with the sacrificial mold part still attached, the mold release operation can be easily performed. In particular, when manufacturing minute sintered material molded bodies, a plurality of sintered material molded bodies can be released from the mold together with the sacrificial mold part, so chipping and the like can be effectively prevented. Further, subsequent handling can be performed easily.

On the other hand, while the sacrificial mold part completely disappears in the binder removal process, in the sintered material molded body, only the binder component disappears, so when the sacrificial mold disappears, the part that supports the sintered material molded body disappears. However, there is a possibility that deformation etc. may occur. Furthermore, if the shrinkage rate of the sacrificial mold part in the binder removal process is different from the shrinkage rate of the sintered material molded body, unexpected stress will act on the sintered material molded body, and the dimensional accuracy and shape accuracy of the molded body will deteriorate. There is a risk of a decline.

In order to avoid the above-mentioned disadvantages, the sacrificial mold part can be configured to include a powdered resin having a predetermined particle size and a sacrificial binder component filled between the powdered resin. The sacrificial binder component of the sacrificial mold part is set so that it melts in the sacrificial mold part molding process, but does not melt in the molding process, and disappears in the binder removal process. The powdered resin is set so as not to melt in the sacrificial mold part molding step and the molding step, but to disappear in the binder removal step. The temperature at which the sacrificial binder component of the sacrificial mold part and the organic binder of the sintered material molded body disappear in the binder removal step can be set lower than the vanishing temperature of the powdered resin.

According to the above configuration, the organic binder of the sintered material molded body and the sacrificial binder component of the sacrificial mold part can be eliminated first. At this time, the powdered resin has not disappeared, and the organic binder in the sintered material molded body can be eliminated while the sintered material molded body is held in the powdered resin. This can prevent deformation of the sintered material molded body during the binder removal process. Thereafter, the binder removal process is completed by disappearing the powdered resin.

That is, the binder removal step includes a first sacrificial mold part disappearing step in which the sacrificial binder component contained in the sacrificial mold part and the organic binder constituting the sintered material molded body disappear; The process includes a second sacrificial mold part disappearing step in which the shaped resin disappears. This makes it possible to remove the binder while holding the sintered material molded body in the sacrificial mold part. Furthermore, preferably, the sacrificial binder component is configured to disappear before the organic binder of the sintered material compact starts to disappear. This makes it possible to make the sacrificial mold part porous and to allow superheated steam to pass through it to eliminate the organic binder of the sintered material molded body, and then to eliminate the powdered resin. The removal of the binder can be further promoted.

Further, in the binder removal step, it is preferable that the shrinkage rate of the sacrificial mold part when the sacrificial binder component disappears is set to be the same as the shrinkage ratio of the sintered material molded body. Thereby, it becomes possible to shrink the sacrificial mold part in accordance with the contraction of the sintered material molded body, and it is possible to improve the shape accuracy and the like of the sintered material molded body.

Further, the sacrificial mold part is configured to include a powder that is not sintered with the sintered powder and a binder component, and in the binder removal step and the sintering step, the sintered material molded body is sintered. These steps can be carried out while keeping the powder free.

By employing the above configuration, it is possible to prevent deformation not only in the binder removal process but also in the sintering process. Further, it is preferable that the shrinkage rate of the sacrificial mold part at least in the binder removal process is set to be the same as the shrinkage rate of the sintered material molded body. Thereby, the shape accuracy of the sintered material molded body after the binder is removed can be further improved.

For example, a metal powder may be used as the sintered powder, and a powder made of a ceramic material may be used as the non-sintered powder. Powder formed from a ceramic material has a higher sintering temperature than metal powder, and does not sinter at the temperature at which the metal powder is sintered. The ceramic powder can be easily removed from the metal sintered body after the metal powder is sintered. In addition, since the ceramic powder is molded into the shape of the holding part of the sintered powder, it is possible to hold the sintered material molded body containing the metal powder with high precision and perform the sintering process. becomes.

Furthermore, the sintered material molded body can be sintered while being held in the sacrificial mold part that is simultaneously sintered. That is, the sacrificial mold portion includes a powder that is sintered in the sintering step but is not sintered with the sintered powder, and a sacrificial binder. In the binder removal step, the organic binder and the sacrificial binder disappear, and in the sintering step, the sintered material molded body is sintered together with the sacrificial mold part, and the sacrificial binder is then sintered. In the mold part removal step, the sacrificial mold part is separated and removed.

Since the sacrificial mold part does not disappear during the sintering process, the sintering process can be performed while the sintered material molded body is held with high accuracy. Therefore, deformation of the sintered material compact during the sintering process can be effectively prevented.

Although the powders constituting the sacrificial mold part are sintered together, it is preferable that the sintered material constituting the sintered material compact be made of a material that is not sintered. For example, when a sintered material molded body is constructed using metal powder, metal powder or ceramic powder that is not sintered with the metal powder can be used.

When a sacrificial mold part is employed, it is preferable to set the shrinkage rate in the binder removal process and the shrinkage rate in the sintering process to be the same. Thereby, it becomes possible to perform the degreasing step and the sintering step while maintaining the shape of the sintered material molded body with high accuracy, and it is possible to improve the shape accuracy of the sintered material molded body.

The organic binder contains at least 20 to 40 vol% of a thermoplastic resin whose binder component has a moisture absorption rate of 0.05% or less, and at least 20 to 40 vol% of an organic compound having a melting point of 100°C or less. It is preferable that the amount of the organic binder added is set to 30 to 70 vol % with respect to the sintered powder, and these members are heated and kneaded to prepare a molding material.

By employing the organic binder containing at least 20 to 40 vol% of the thermoplastic resin having a moisture absorption rate of 0.05% or less, the resin component is thermally decomposed in superheated steam without swelling. Therefore, the occurrence of cracks and the like can be effectively prevented. When a resin with a moisture absorption rate exceeding 0.05% is blended in an amount exceeding 40 vol %, it tends to absorb moisture from superheated steam, and cracks are likely to occur due to swelling.

Furthermore, by including at least 20 to 40 vol % of an organic compound with a melting point of 100° C. or lower, the fluidity of the molding material in the molding process can be ensured, and the toughness of the sintered material molded body can also be improved.

Further, it is preferable that the powder sintered body formed from the molding material obtained in the molding material preparation step is subjected to a binder removal step in superheated steam at a maximum temperature of 800° C. or lower.

Thereby, the binder of the above-mentioned composition can be efficiently decomposed and eliminated. Note that, as described above, the binder component can be set depending on the form of the sintered material molded body.

Thereafter, a sintering process is performed by increasing the temperature of superheated steam to 900°C to 1500°C. If the temperature of the superheated steam in the sintering step is less than 900° C., residual carbon from the binder cannot be sufficiently decomposed and eliminated. On the other hand, if the temperature exceeds 1500°C, the sintered material will melt and problems such as deformation will easily occur.

As the thermoplastic resin having a moisture absorption rate of 0.05% or less, it is preferable to employ polyethylene, polypropylene, or ethylene vinyl acetate polymer.

Organic compounds with a melting point of 100°C or less include paraffin wax, fatty acid ester, fatty acid amide, phthalate ester, microcrystal wax, polyethylene wax, polypropylene wax, carnauba wax, montan wax, urethanized wax, maleic anhydride modified wax, An organic compound consisting of stearic acid and a polyglycol compound can be employed.

In particular, it is more preferable that the component constituting the organic binder contains at least 5 to 40 vol% of one or more thermoplastic resins selected from polyethylene, polypropylene, polystyrene, and ethylene-vinyl acetate copolymers.

The type of sintered powder according to the present invention is not particularly limited. For example, stainless metal powder or zirconia ceramic powder can be used. Moreover, the powder sintered compact can be used for various purposes.

The binder removal step and the sintering step can be performed in a short time, cracks, cracks, etc. are less likely to occur, and moreover, a highly accurate powder sintered body can be formed.

FIG. 3 is a diagram schematically showing a state in which a binder removal process and a sintering process are performed using superheated steam in a furnace body. 2 is a diagram showing a state before the start of a degreasing process using the apparatus shown in FIG. 1. FIG. It is a figure which shows the state in the middle of a binder removal process. It is a figure showing the state where the binder removal process was completed. FIG. 3 is a diagram schematically showing a sintering process. FIG. 2 is a diagram schematically showing the configuration of a sintered material molded body. It is a figure which shows typically the state of the sintered material compact in the middle of a binder removal process. FIG. 3 is a diagram schematically showing the state of the sintered material molded body after the binder removal process is completed. FIG. 3 is a diagram schematically showing a state in which the sintering process has been completed. It is a figure which carries out the binder removal process while holding a sintered material molded body by the holding member which allows superheated steam to pass through. It is a figure which shows typically the structure of the sintered material molded body which has a different part of organic binder. It is a figure which shows typically the state in the middle of the binder removal process of the sintered material molded body which has a different part of organic binder. FIG. 3 is a diagram schematically showing the state of a sintered material molded body having different portions of organic binder after a binder removal process is completed. It is a figure which shows the process of forming a sacrificial mold part. 15 is a diagram showing a process of forming a sintered material molded body using the sacrificial mold part shown in FIG. 14. FIG. FIG. 16 is a diagram schematically showing a state in which the sacrificial mold part and the sintered material molded body shown in FIG. 15 are taken out from the mold device. 17 is a diagram schematically showing a state in which the binder is removed from the sacrificial mold part and the sintered material molded body shown in FIG. 16. FIG. 18 is a diagram schematically showing a state in which the sacrificial mold part has disappeared from the molded body shown in FIG. 17. FIG. FIG. 19 is a diagram schematically showing the state after sintering the molding material molded body shown in FIG. 18. FIG. 2 is a diagram schematically showing a cross section of a sintered material molded body provided with a binder removal regulating portion. FIG. 21 is a diagram schematically showing the state of the sintered material molded body shown in FIG. 20 during the binder removal process. It is a figure which shows typically the state after the binder removal process of the sintered material molded object shown in FIG.19 and FIG.20 is completed. 17 is a schematic diagram showing an example in which powder constituting a sacrificial mold part is sintered, and is a drawing corresponding to FIG. 16. FIG. 24 is a diagram showing a state in which the sacrificial binder and the organic binder have disappeared from the sacrificial mold part and the sintered material molded body shown in FIG. 23. FIG. FIG. 25 is a diagram showing a state in which the sintered material molded body shown in FIG. 24 is sintered. It is a figure which shows the state which separated the sintered material molded body from the sacrificial mold part. It is a figure which shows another embodiment of a sacrificial mold part. 28 is a diagram showing a state in which the binder has been removed from the molded body shown in FIG. 27. FIG. FIG. 29 is a diagram showing a state in which the sintered material molded body shown in FIG. 28 and the sacrificial mold part are integrally sintered. FIG. 30 is a diagram showing a state in which the powder sintered molded body and the sacrificial mold part shown in FIG. 29 are separated.

Embodiments of the present invention will be specifically described below. As shown in FIG. 1, a superheated steam degreasing and sintering device 1 according to the present embodiment includes a furnace body 2 that accommodates a sintered material compact 10, and a superheated steam generator that supplies superheated steam 6 to the furnace body 2. 3, an injection nozzle 5 for injecting and supplying superheated steam 6 from above into the furnace body 2, and discharge ports 7, 7 for discharging superheated steam containing components obtained by decomposing the binder from inside the furnace body 2. It is configured with.

As the superheated steam generator 3, various commercially available superheated steam generators can be used. Inside the furnace body 2, a sintered material molded body 10 is placed on a ceramic stand 9, and is configured such that superheated steam can be applied from above.

As shown in FIGS. 2 and 3, the sintered material molded body 10 is formed by molding a molding material 13 containing a sinterable sintered powder 11 and an organic binder 12. As shown in FIGS. The method of molding the above-mentioned molding material is not particularly limited. For example, it can be formed using various molding techniques such as compression molding, injection molding, and extrusion molding.

Various powders can be used as the sintered powder. For example, metal powder or ceramic powder with the required particle size can be used. The particle size of the powder can be appropriately set depending on the above-mentioned molding method and the like.

In the present invention, stainless steel powder with a predetermined particle size is adopted as the sintered powder 11, and an organic binder is kneaded with the stainless steel powder to prepare a molding material, which is then injection molded to form the sintered material. It forms a body 10.

The organic binder in this embodiment contains at least 20 to 40 vol% of a thermoplastic resin having a moisture absorption rate of 0.05% or less, and at least 20 to 40 vol% of an organic compound having a melting point of 100°C or less. , constituting the molding material 13.

As the thermoplastic resin, it is preferable to employ one or more thermoplastic resins selected from polyethylene, polypropylene, polystyrene, and ethylene-vinyl acetate copolymers. In addition, the above-mentioned organic compounds include paraffin wax, fatty acid ester, fatty acid amide, phthalic acid ester, microcrystalline wax, polyethylene wax, polypropylene wax, carnauba wax, montan wax, urethanized wax, maleic anhydride modified wax, stearic acid, and Organic compounds consisting of polyglycol compounds can be used. The types and blending ratios of the thermoplastic resin and the organic compound can be set depending on the molding method, the form of the molded article, and the like.

2 to 5 schematically show the binder removed state in the degreasing process of the sintered material compact. In this embodiment, superheated steam at a temperature 5° C. higher than the temperature at which a part of the adopted organic binder starts to disappear is flowed from above to below the sintered material compact 10 using the injection nozzle 5. let The superheated steam 6 is made to flow along the surface of the sintered material molded body 10 and is discharged from the discharge ports 7 provided on the sides of the furnace body 2 . In FIG. 1, the flowing superheated steam 6 is shown to be discharged into the atmosphere, but it can also be circulated to the superheated steam generator 3.

As shown in FIG. 1 , by applying superheated steam 6 at the above temperature to the surface of the sintered material molded body 10, the organic binder in the sintered material molded body 10 can be sequentially disappeared from the surface side. can. Moreover, in this embodiment, since the superheated steam 6 at a constant temperature 5° C. higher than the vanishing start temperature of the adopted organic binder is applied, the temperature inside the sintered material molded body 10 does not exceed the above temperature. .

As mentioned above, superheated steam 6 performs debinding using a mechanism different from debinding using air. It can be set lower than in other cases. Therefore, it is possible to start removing the binder from the surface of the sintered material compact 10 at a temperature below the temperature at which the organic binder rapidly expands or decomposes. If the temperature of the superheated steam becomes higher than the temperature at which binder removal by superheated steam starts by exceeding 10° C. , there is a high possibility that the organic binder will rapidly expand or decompose.

By removing the binder within a range where the temperature of the superheated steam does not exceed 5°C higher than the temperature at which the organic binder starts to decompose, the organic binder inside the sintered material compact 10 will not expand rapidly. , it will not be disassembled. Therefore, in the binder removal step, it is possible to effectively prevent cracks from occurring within the sintered material molded body 10. The temperature of the superheated steam 6 can be set in a range that does not exceed 10° C. above the disappearance start temperature of the organic binder, depending on the disappearance characteristics of the organic binder.

On the other hand, if the temperature of the superheated steam is set to a temperature 5° C. higher than the temperature at which the organic binder starts to disappear, it may not be possible to completely eliminate the organic binder. For this reason, after a predetermined period of time has elapsed or after a predetermined amount of the organic binder has disappeared, it is preferable to raise the temperature of the superheated steam to a temperature higher than the temperature at which all the organic binder disappears.

As shown in FIG. 4, by raising the temperature of the superheated steam 6 above the temperature at which all the organic binder disappears , the organic binder can be completely disappeared, as shown in FIG. Thereafter, the temperature of the superheated steam is increased to sinter the sintered material molded body 10. The above sintering temperature can be set depending on the type of sintered powder. For the stainless steel powder employed in this embodiment, it is preferable to apply superheated steam at about 1200°C. As shown in FIG. 5, the sintered powder compact 14 shrinks by 10 to 20% compared to the sintered material compact 10 because the gaps between the sintered powders are eliminated in the sintering process.

6 to 9 schematically show the internal state of the sintered material molded body 10 during the binder removal process and the sintering process of the sintered material molded body. In this embodiment, the organic binder 22 is composed of two types of binder components 22a and 22b having different vanishing temperatures, and in these figures, the components of the organic binders 22a and 22b are shown as circular particles with different diameters. There is.

In this embodiment, the organic binder 22 includes a binder component 22a that disappears at low temperatures and a binder component 22b that disappears at high temperatures. As the binder component 22a that disappears at the low temperature, an organic compound having a melting point of 100° C. or lower is used. On the other hand, as the binder component 22b that disappears at high temperatures, the above-mentioned thermoplastic resin having a moisture absorption rate of 0.05% or less is used. The blending ratio of each binder component is set within the above-mentioned range depending on the molding method and the like.

First, superheated steam is generated at a temperature 1 to 5° C. higher than the disappearance start temperature of the binder component 22a that disappears at a low temperature and below the temperature at which the binder component 22b that disappears at the high temperature starts to disappear, The first binder removal step is performed by acting on the sintered material molded body 10 in the same manner as in the embodiment described above.

The temperature of the superheated steam is set to be higher than the disappearance start temperature of the binder component 22a that disappears at the low temperature, and lower than the disappearance start temperature of the binder component 22b that disappears at the high temperature. In the first binder removal step, the binder component 22a that disappears at the low temperature is selectively disappeared.

In this embodiment, the temperature of the superheated steam can be kept constant and it can be applied to the surface of the sintered material molded body 10, so that it disappears at a low temperature while leaving behind the binder component 22b that disappears at a high temperature. It is possible to selectively eliminate only the binder component 22a. Moreover, since the airflow of superheated steam is applied to the surface of the sintered material compact 10 to eliminate these binder components, the binder components disappear more efficiently and at a lower temperature than in the conventional method of maintaining the inside of the furnace at a constant temperature. It becomes possible to selectively eliminate only 22a. Therefore, as shown in FIG. 7, a porous sintered material molded body 10 is formed by eliminating the binder component 22a that disappears at low temperatures.

Thereafter, the temperature of the superheated steam is raised to a temperature above which the binder component 22b, which disappears at high temperatures, disappears, and the superheated steam is allowed to act on the sintered material molded body 10. Since the sintered material molded body 10 is porous, the binder removal process can be performed while allowing the superheated steam to penetrate into the inside of the sintered material molded body. As a result, as shown in FIG. 8, it becomes possible to efficiently remove the organic binder while preventing the occurrence of cracks and the like.

Thereafter, the temperature of the superheated steam is increased to a temperature higher than the sintering temperature of the sintered powder 21, and a sintering process is performed to form the powder sintered body 24 shown in FIG. 9.

As shown in FIGS. 2 and 3, the sintered material compact 10 is held on a ceramic stand 9 in a furnace. Since the table 9 has low permeability to superheated steam , the superheated steam does not easily act on the portion in contact with the table 9. For this reason, removal of the binder from the bottom of the sintered material molded body is inhibited, and degreasing of the portion near the center of the bottom of the table 9 is delayed. For this reason, depending on the shape of the sintered material molded body, unexpected deformation or the like may occur in the portion in contact with the table 9.

In order to eliminate the above-mentioned disadvantages, as shown in FIG. 10, superheated steam 36 can pass through the binder removal process and/or the sintering process, and can be displaced in response to the contraction of the sintered material molded body 33. This can be carried out by being held by a holding member 39 made of particles 39a.

Further, in this embodiment, the superheated steam 36 can be ejected into the furnace body 2 not only from the nozzle 35a provided above but also from the nozzle 35b provided below the holding member 39 , that is, on the bottom surface of the furnace. It is configured as follows. The superheated steam ejected from the nozzle 35b provided at the bottom of the furnace is made to flow toward the sintered material molded body, and is made to act on the bottom surface of the sintered material molded body. With the above configuration, it becomes possible to apply the superheated steam 36 to the entire periphery of the sintered material molded body 33, and the inconvenience when the above-mentioned table 9 is adopted is eliminated.

Moreover, the holding member 39 is made up of particles 39a, and is configured to be able to be displaced or deformed in accordance with the contraction of the sintered material molded body 33. Therefore, in the binder removal process and the sintering process, it is possible to effectively prevent unexpected deformation or the like from occurring in the holding portion of the sintered material molded body 33.

Furthermore, in the state shown in FIG. 10, the temperature of the superheated steam 36 can be raised to a temperature higher than the sintering temperature of the sintered powder 31, and a sintering process can be performed following the binder removal process. In the sintering process, the particles 39a can be displaced or deformed in accordance with the contraction of the sintered material compact, so that a powder sintered compact with high shape accuracy can be formed.

11 to 13 show other embodiments of the binder removal process.

In this embodiment, in the above-mentioned forming step, a sintered material molded body 43 is formed that includes at least two or more portions in which binder components having different disappearance start temperatures and/or disappearance completion temperatures are blended. As shown in FIG. 11, the same sintered powder 41 is used in all parts, but the type of organic binder is different in the center part and both sides.

An organic binder 42a that disappears at high temperatures is used in the both sides, while an organic binder 42b that disappears at low temperatures is used in the center. Specifically, the organic binder 42a is a resin binder containing polyethylene resin, and the organic binder 42b is an organic binder containing polyacetal resin.

The method of forming the sintered material compact having the above structure is not particularly limited. For example, when injection molding is employed, an integral sintered material molded body can be formed by so-called two-color molding. Alternatively, the above-mentioned side portions and the center portion may be separately molded and bonded by melting the binder component on the bonding surfaces.

The sintered material compact 43 is first treated with superheated steam at a temperature higher than the temperature at which the organic binder 42b, which disappears at low temperatures, starts to disappear and lower than the temperature at which the organic binder 42a starts to disappear. Perform the binder removal process. Since the temperature of the superheated steam can be controlled with very high precision, only the organic binder 42b that disappears at the low temperature can be selectively eliminated. Although both binders may start to disappear depending on the disappearance temperature, at least 40 to 80% of the organic binder 42a should be configured so that it does not disappear when the organic binder 42b completely disappears. is desirable.

After the organic binder 42b that disappears at low temperatures disappears, the temperature of the superheated steam is raised to a temperature at which the organic binder that disappears at high temperatures disappears, and a second binder removal step is performed. Thereby, the binder in the sintered material molded body 43 can be completely eliminated.

If the above method is adopted, it becomes possible to preferentially eliminate the binder in a predetermined portion of the sintered material molded body 43. Normally, the resin binder disappears uniformly from the vicinity of the surface of the sintered material molded body 43, but depending on the form, the shape accuracy etc. may be improved by preferentially removing the binder from a predetermined portion or delaying it. There is. In addition, when superheated steam is applied, the speed of the airflow of superheated steam on the surface of the sintered material compact may vary depending on the position in the furnace and the shape of the compact, so the degreasing speed will differ. . For this reason, unexpected deformation or the like may occur during the degreasing process. By employing the above method, it becomes possible to adjust the binder removal speed at a predetermined portion and form a powder sintered body with a complex shape that has been difficult to manufacture up to now.

14 to 18 show examples in which the present invention is applied to a powder sintered body molded using a sacrificial mold part.

As shown in FIG. 14, in this embodiment, first, a sacrificial mold part 64 is molded using a mold apparatus 60 that includes an upper mold 61 and a lower mold 62. An upper mold inner surface 61a and a lower mold inner surface 62a are formed between the upper mold 61 and the lower mold 62. A molding space is formed between these inner surfaces, and a sacrificial mold material 63 is injected into the molding space from a sacrificial member injection port 67 provided in the upper mold 61 to form a sacrificial mold part 64.

Next, the upper mold 61 is replaced with a second upper mold 71. A molding material 53 containing a sinterable powder 51 and an organic binder 52 is placed between the second upper mold 71 and the sacrificial mold part 64. The sintered material molded body 70 to which the sacrificial mold part 64 is attached is formed by being injected from the injection port 65 and embedded in the sacrificial mold part 64 .

The sintered material molded body 70 is released from the molds 71 and 62 together with the sacrificial mold part 64. Therefore, there is no fear that the sintered material molded body 70 will be damaged during demolding. Furthermore, subsequent handling can be performed easily.

As shown in FIG. 16, in this embodiment, the sacrificial material 63 includes a powdered resin 65 having a predetermined particle size and a sacrificial binder component 66 filled between the powdered resin 65. Consists of. On the other hand, the sintered material molded body 70 is composed of a molding material 53 containing a sintered powder 51 and an organic binder 52, similar to the embodiment described above.

The sacrificial binder component 66 is set so that it melts in the sacrificial mold part molding step, does not melt in the molding step of injecting the molding material 53, and disappears in the binder removal step. The powdered resin 65 is set so as not to melt in the sacrificial mold part molding process and the molding process, but to disappear in the binder removal process. In the binder removal step, the temperature at which the sacrificial binder component 66 of the sacrificial mold part 64 and the organic binder 52 of the sintered material mold disappear is set lower than the vanishing temperature of the powdered resin 65. ing.

For example, a binder component containing polyethylene may be used for the sacrificial binder component 66 and the organic binder 52, while a thermosetting resin material such as urethane resin or polyester resin may be used for the powdered resin 65. can.

Superheated steam is applied to the sintered material molded body 70 and the sacrificial mold part 64 of the above form at a temperature higher than the temperature at which the sacrificial binder component 66 and the organic binder 52 disappear, but at which the powdered resin 65 does not disappear. Let it work. By applying superheated steam at the above temperature for a predetermined period of time, as shown in FIG. 17, the sintered material molded body 70 from which the binder has been removed and the powdered resin 65 of the sacrificial mold part 64 remain. I can do it.

The shrinkage rate of the sacrificial mold part 64 when the sacrificial binder component 66 disappears is set to be the same as the shrinkage rate of the sintered material molded body 70 when the organic binder 52 disappears. Therefore, the binder removal process can be performed while effectively preventing deformation or the like during the binder removal process.

Thereafter, by raising the superheated steam to a temperature higher than the temperature at which the powdered resin 65 disappears, the powdered resin 65 disappears, as shown in FIG. 18. This completes the binder removal process for the sintered material molded body 70.

In this embodiment, the organic binder in the sintered material molded body can be made to disappear while the sacrificial mold part 64 holds the sintered material molded body 70 . Moreover, it becomes possible to apply superheated steam to the entire circumference of the sintered material molded body 70 through the sacrificial mold part 64, which has become porous by eliminating the sacrificial binder component in the sacrificial mold part 64. , it is possible to improve the binder removal efficiency, improve shape accuracy, and prevent cracks and the like.

Thereafter, the superheated steam is raised to a temperature higher than the sintering temperature of the sintered powder, and a powder sintered body 74 shown in FIG. 19 is formed.

20 to 22 show an embodiment in which a binder removal regulating portion 90 is provided to regulate disappearance of the organic binder 82 at a predetermined portion of the sintered material molded body 80 in the binder removal process.

The sintered material molded body 80 is formed to include a sintered powder 81 and an organic binder 82, similarly to the sintered material molded body according to the first embodiment. In this embodiment, a sintered material molded body 80 including a flat base 91 and a protrusion 92 protruding from the upper surface of the base is molded. Further, the binder removal regulating portion 90 is provided to cover the corner portions of the base portion 91 and the projection portion 92. The binder removal regulating section 90 is made of a resin material having a higher vanishing temperature than the organic binder 82 .

First, superheated steam is applied to the sintered material molded body 80 having the above configuration, at a temperature higher than the temperature at which the organic binder 82 starts to disappear, but at which the binder removal regulating section 90 does not disappear. Then, as shown in FIG. 21, the disappearance of the organic binder 82 in the vicinity of the portion where the binder removal regulating portion 90 is provided is restricted, and the removal of the binder from other portions proceeds. Thereafter, the binder removal regulation part 90 is made to disappear by applying superheated steam at a temperature higher than that at which the binder removal regulation part 90 disappears.

With the above configuration, the binder removal process can proceed while the corners of the projections 92 of the sintered material molded body 80 are protected. Therefore, in the binder removal step, it is possible to delay or accelerate the debinding of portions where deformation or the like is likely to occur, and further to perform the binder removal step while adjusting the degree of binder removal. Therefore, deformation and cracking during the binder removal process can be effectively prevented.

23 to 26 show an embodiment in which the sintered material molded body 70 is sintered while being held in a sacrificial mold part 164 that is sintered at the same time. As shown in FIG. 23, the powder 165 constituting the sacrificial mold part 164 is sintered in the sintering process, while the sintered powder 51 constituting the sintered material compact 70 is not sintered. has been done. Note that the sintered powder 51 and organic binder 52 constituting the sintered material molded body 70 are the same as those in the embodiment described above, so a description thereof will be omitted.

The sacrificial binder 166 has the same components as the organic binder 52. In the binder removal process, the sacrificial mold part 164 is configured so that the binder is removed at the same shrinkage rate as the sintered material compact 70. Therefore, as shown in FIG. 24, in the binder removal process, the binder can be removed while the sintered material molded body 70 is protected by the sacrificial mold part 164.

Furthermore, in this embodiment, the powder 165 constituting the sacrificial mold part 164 is set to be sintered at the same shrinkage rate as the sintered material molded body 70 in the sintering process. Therefore, as shown in FIG. 25, the sintered material molded body 70 is integrally sintered with the sacrificial mold part 164. Also, in the sintering process, the sintering process can be performed while protecting the sintered material molded body 70 with the sacrificial mold part 164 .

Since the sacrificial mold part 167 after sintering in FIG. 25 is made of a material that is not sintered with the powder sintered molded body 151, it can be easily separated as shown in FIG. 26. Note that the powder 165 constituting the sacrificial mold part 164 is sintered in a pre-sintered state, that is, sintered so that the strength is lower than that of the powder sintered compact 151, and then the sacrificial mold part 167 is destroyed. It is also possible to separate the powder sintered molded body 151 by using the sintered powder body 151.

For example, a low melting point ceramic powder may be used as the powder 165 constituting the sacrificial mold part 164, and stainless steel powder may be used as the sintered powder. Preferably, the ceramic powder is pre-sintered at a temperature at which the stainless steel powder finishes sintering.

27 to 30 show an embodiment in which the sacrificial mold part 264 is formed in a form that allows superheated steam to flow.

Note that the powder 265 and sacrificial binder 266 of the sacrificial mold part 264, and the sintered powder 251 and organic binder 252 of the sintered material molded body 273 are the same as in the embodiment described above.

In this embodiment, in the step of molding the sacrificial mold part 264, a region is provided in which the powder 265 is not present and the sacrificial mold part 264 is molded only with the sacrificial mold binder 266.

In the area where the powder 265 is not present, the sacrificial binder disappears in the binder removal process, and the area becomes pore-shaped. In this embodiment, a horizontal hole 271 extending parallel to the mounting surface of the furnace and a vertical hole 270 communicating with the horizontal hole 271 and communicating with the lower surface of the sintered material compact 273 are formed. Thereby, the superheated steam 6 can be guided to the lower surface of the sintered material molded body 273, and the binder removal process and the sintering process can be performed efficiently, and the occurrence of cracks and deformation can be effectively prevented.

Examples of the present invention will be shown below. In the examples, a molding material with the following components was prepared, and a rectangular parallelepiped test piece of 10 x 20 x 5 mm was molded to conduct an experiment.

Example 1
Stainless steel metal powder (SUS316L: average particle size 7μm) 60vol%
Organic binder: 40vol%
(1) Polypropylene: 20vol%
(2) Ethylene vinyl acetate copolymer: 20 vol%
(3) Paraffin wax: 50vol%
(4) Stearic acid: 10vol%

Example 2
Stainless steel metal powder (SUS317: average particle size 7μm) 60vol%
Organic binder: 40vol%
(1) Polypropylene: 20vol%
(2) Polyethylene: 20vol%
(3) Paraffin wax: 50vol%
(4) Stearic acid: 10vol%

[Test method and test results according to Example 1 and Example 2]
In Examples 1 and 2, each stainless steel metal powder and organic binder were heated and kneaded at 160° C. to create a molding material in the form of pellets. Next, an injection molding step was performed at an injection molding temperature of 180° C. to obtain a molded article of the above form. The obtained compact was heated from 50° C. to 800° C. at a rate of 5° C./min using a superheated steam generator to remove the organic binder from the compact. In both Examples 1 and 2, it was confirmed by residual carbon analysis (Horiba, Reco carbon amount measuring device) that the amount of residual organic binder was 5% or less.

The obtained binder-free molded body was sintered at a maximum temperature of 1350°C, up to 800°C in a hydrogen gas atmosphere, and above 800°C in an argon gas atmosphere , to obtain a powder sintered molded body. The obtained sintered compact was a sound sintered compact with no internal cracks.

Example 3
Zirconia ceramic powder (specific surface area 8 square meters/g): 50vol%
Organic binder: 50vol%
(1) Polypropylene: 10vol%
(2) Ethylene vinyl acetate copolymer: 20 vol%
(3) Paraffin wax: 60vol%
(4) Stearic acid: 10vol%

Example 4
Zirconia ceramic powder (specific surface area 8m ² /g): 50vol%
Organic binder: 50vol%
(1) Polystyrene: 5vol%
(2) Ethylene vinyl acetate copolymer: 25 vol%
(3) Paraffin wax: 60vol%
(4) Stearic acid: 10vol%

[Test method and test results according to Example 3 and Example 4]
For Examples 3 and 4, each zirconia powder and organic binder were heated and kneaded at 160° C. to create a pellet-shaped molding material. Next, the molded material was molded at an injection molding temperature of 180° C. to obtain a sintered material molded body having the above-mentioned form. The obtained sintered material molded body was heated from 50° C. to 800° C. at 3° C./min using a superheated steam apparatus to remove the organic binder from the sintered material molded body. In both Examples 3 and 4, it was confirmed by residual carbon analysis (Horiba, Reco carbon amount measuring device) that the amount of residual organic binder was 5% or less. The obtained sintered material molded body from which the binder had been removed was fired in an air atmosphere at a maximum temperature of 1450°C to obtain a powder sintered molded body of a predetermined shape.

[Comparative example 1]
Tests were conducted under the same conditions using 66 nylon, polyacetal, and polymethyl methacrylate as binders instead of polyethylene, polypropylene, polystyrene, and ethylene vinyl acetate copolymers in the above examples.

[Test results in Comparative Example 1]
Under the same conditions as above, cracks occurred during the superheated steam degreasing process.

[Comparative example 2]
The test pieces having the configurations according to Examples 1 and 2 above were degreased under conventional heating degreasing conditions in a nitrogen atmosphere. In this case, even when the binder was removed under the condition of 0.5° C./min, deformation occurred during heating and a sound degreased body could not be obtained.

[Comparative example 3]
When the test pieces with the configurations of Examples 3 and 4 were degreased under the conventional heating degreasing conditions in an air atmosphere, cracks occurred inside even when degreasing was carried out under the conditions of 0.1°C/min, resulting in healthy degreasing. Couldn't get the body.

[Consideration]
When a material with a moisture absorption rate exceeding 0.05% was used as a thermoplastic resin binder, cracks occurred even under heating conditions of 1° C./min. When polyethylene, polypropylene, polystyrene, or ethylene vinyl acetate copolymer having a moisture absorption rate of 0.05% or less was used as a thermoplastic resin binder, no cracks occurred even at 5° C./min.
Since these hydrocarbon resins have very low water absorption rates of 0.05% or less, it is thought that the resins themselves were thermally decomposed without swelling even in superheated steam.
On the other hand, when polyacetal, nylon, or polymethyl methacrylate with a water absorption rate of 0.05% or more is used as a resin binder, when heated with steam, these resins absorb water and swell, forming a sintered material. It is thought to cause cracks in the body.

The scope of the present invention is not limited to the above embodiments and examples. The present invention can be applied to various forms of molded articles other than the form of the sintered material molded body described in the embodiments. Furthermore, the constituent components of the sintered material molded body described in the embodiments are not limited, and various sintered powders, various organic binders, etc. can be employed.

Since the binder removal process and the sintering process can be performed in a short time, energy efficiency is high, cracks, cracks, etc. are less likely to occur, and moreover, a highly accurate powder sintered body can be formed.

6 Superheated steam 10 Sintered material molded body 11 Sintered powder 12 Organic binder 13 Molding material 14 Powder sintered molded body

Claims (6)

Superheated steam debinding sintering involves degreasing a sintered material molded body formed into a predetermined shape from a molding material containing sinterable sintered powder and an organic binder by applying superheated steam and sintering it at a predetermined temperature. a tying device,
a furnace body that accommodates a sintered material compact;
a superheated steam generator that supplies superheated steam to the furnace body;
an injection nozzle that injects and supplies superheated steam from above into the furnace body;
and an exhaust port for discharging superheated steam containing components obtained by decomposing the binder from the furnace body,
comprising a plurality of the injection nozzles that flow the superheated steam toward the surface of the sintered material molded body,
A superheated steam degreasing and sintering apparatus comprising a holding member capable of holding the sintered material molded body and applying superheated steam to the entire periphery including the lower surface of the sintered material molded body. The plurality of injection nozzles include an injection nozzle capable of injecting superheated steam from above the furnace body toward the sintered material compact;
The superheated steam degreasing and sintering apparatus according to claim 1, further comprising an injection nozzle capable of injecting superheated steam toward the sintered material molded body from below the furnace body. While flowing the superheated steam toward the surface of the sintered material molded body,
The superheated steam degreasing and sintering apparatus according to claim 1 or 2, comprising the injection nozzle that causes the sintered material to flow along the entire surface of the molded body. The superheated steam degreasing and sintering apparatus according to claim 1, comprising a superheated steam generator and the injection nozzle that continuously flow superheated steam at a predetermined temperature toward the surface of the sintered material compact. The holding member allows superheated steam to pass through, and
The superheated steam degreasing and sintering apparatus according to claim 2, wherein the superheated steam injected from the injection nozzle provided on the bottom surface of the furnace body is made to flow toward the bottom surface of the sintered material compact. A sintered material formed into a predetermined shape from a molding material containing a sinterable sintered powder and an organic binder , which is performed using the superheated steam degreasing and sintering apparatus according to claims 1 to 5. A superheated steam degreasing and sintering method in which a molded body is degreased by applying superheated steam and sintered at a predetermined temperature,
A superheated steam degreasing and sintering method in which the superheated steam at a predetermined temperature is continuously flowed toward the entire surface of the sintered material molded body including the lower surface .

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