JPH06207206A - Sintering method for titanium or titanium alloy and ceramic used in this method - Google Patents

Abstract

PURPOSE:To obtain the nonoxidative sintered body of a titanium powder green compact by using ceramics for sintering having a specific chemical compsn. CONSTITUTION:The ceramics for sintering consisting of 0.5 to 90wt.% CaO and the balance ZrO2 is used as an intra-furnace jig. The content of the CaO needs to be 0.5 to 90wt.% at this time. An effect of preventing the oxidation of the titanium and titanium alloy or reducing effect of the titanium and titanium alloy is insufficient if the content. thereof is below 0.5wt.%. The ceramics turns to tetragonal crystals even at ordinary temp. and high temp. and its thermal impact property and heat resistance are improved if the content exceeds the above-mentioned range. As a result, the sintered body is not oxidized at the time of the sintering treatment of the powder green compact of the titanium and titanium alloy and the sintered body of the titanium and titanium alloy having excellent mechanical characteristics is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sintering titanium or a titanium alloy and a ceramic used therefor.

[0002]

2. Description of the Related Art A powder sintered body of titanium or a titanium alloy is produced by a press molding method, an extrusion molding method, an injection molding method or the like. That is, it is obtained by subjecting a green compact obtained by molding a kneaded material of titanium powder, titanium alloy powder, additive element powder, etc. and a binder to binder removal sintering and then sintering at a temperature of 950 to 1400 ° C. However, if the oxygen content of the sintered body is high, the mechanical properties of the sintered body, especially the ductility, are significantly deteriorated.

Therefore, the oxidation of titanium is reduced by performing the binder removal heat treatment in an inert gas atmosphere or in a vacuum. Further, at the time of sintering, the sintering is performed in a high vacuum atmosphere, or an oxygen scavenger such as metallic calcium is placed in the vicinity of the treated body to prevent oxidation. However, no attention has been paid to jigs in the furnace such as setters and trays, and general sintered ceramics of alumina and magnesia are used. However, at high temperatures, oxygen was transferred from these ceramics to the treated body, and a sintered body having excellent mechanical properties could not be obtained.

It is also conceivable to use calcia sintered ceramic, which is less likely to be decomposed than alumina, as a jig in the furnace. However, calcia easily absorbs water, and if calcia containing water is used, the dew point of the atmosphere in the furnace deteriorates,
On the contrary, the processed product is oxidized. Therefore, in order to avoid absorption of water, it is necessary to store the calcia in a vacuum when it is not used, and there is a problem that it is inconvenient to handle.

[0005]

A method of sintering titanium or titanium alloy having excellent mechanical properties by using a sintering ceramic that does not oxidize the sintered body during the sintering process of powder compacts of titanium and titanium alloy. To provide.

[0006]

Means for Solving the Problems The above problems can be solved by a sintering ceramic of titanium or a titanium alloy containing 0.5 to 90% by weight of CaO and the balance ZrO ₂ .

[0007]

The present invention provides a titanium or titanium alloy, which is made of a ceramic composed of an oxide of calcium which forms a more stable oxide than titanium and an element of zirconium which forms an oxide which is inferior to titanium and is more stable. The sintered compact is characterized in that it is not oxidized during the sintering process of the powder compact, it is difficult to absorb water and it is easy to handle.

The ceramic of the present invention can be prepared by a usual method, for example, by mixing calcia powder and zirconia powder, press-molding and sintering in air at a temperature of 1300 to 1400 ° C. The average particle size of each of the calcia powder and the zirconia powder is preferably 0.1 to 1 μm.

CaO should be 0.5 to 90% by weight. If it is less than 0.5% by weight, the antioxidation or reduction effect of titanium and titanium alloy becomes insufficient. Furthermore,
The ceramic is orthorhombic at room temperature and the temperature is 1100 ° C.
Since it transforms into a tetragonal crystal in the vicinity, cracks are generated during use due to expansion and contraction during the transition, and thermal shock resistance and heat resistance are poor. However, when 0.5% by weight or more of calcia is contained, tetragonal crystals are formed at room temperature and high temperature, and thermal shock resistance and heat resistance are improved. On the other hand, if it exceeds 90% by weight, it tends to absorb water too much, and if it is not used, such as storing it in a vacuum container, the sintered body will oxidize and the mechanical strength and thermal shock resistance will deteriorate. Will end up.

[0010]

EXAMPLE Titanium powder having an average particle size of 45 μm and a purity of 99.5% by weight or Ti-6% by weight Al—having an average particle size of 45 μm
Using 4% by weight V titanium alloy powder, a molded body was prepared by a press molding method, an extrusion molding method and an injection molding method.

In the press molding method, the powder is kneaded with 2% by weight of paraffin wax having a melting point of 55 ° C. to obtain JIS 6
A mold having a shape corresponding to the No. tensile test piece (JIS Z2201) was filled and pressed with a compressive force of 2000 kgf / cm ² to prepare a molded body.

In the press molding method, the powder, 5% by weight of the paraffin wax, and 1% by weight of an acrylic resin having a specific gravity of 0.91 g / cm ³ were kneaded, and a diameter of 4 was obtained by an extruder.
A line of mm was extruded.

In the injection molding method, the powder, 3.2 wt% of the paraffin wax, 3.2 wt% of the acrylic resin, and 3.2 wt% of reagent grade stearic acid are kneaded and injected. Injection temperature 100 ° C and injection pressure 100 with molding machine
It was injection-molded into a mold having a shape corresponding to the tensile test piece at kgf / cm ² .

These compacts were placed on various flat plate setters shown in Table 1 and heated in an argon stream at a temperature of 500 ° C. to remove the binder, and subsequently in a vacuum furnace at a pressure of 10 ^-5 T.
Sintered at orr and 1250 ° C. for 90 minutes.

The calcia-zirconia ceramic of the setter material is a calcia powder having a purity of 99.9% by weight and an average particle size of 1 μm and a high-purity magnesia powder having an average particle size of 0.15 μm (Toso Co., Ltd., trade name TZ-0). ) Was mixed with a V blender with a V blender, molded at a pressing pressure of 1 ton / cm ² , and then sintered at a temperature of 1300 ° C. in the atmosphere. Calcia was produced by molding and sintering the above calcia powder in the same manner. Alumina was manufactured by Mitsui Kinzoku Co., Ltd., trade name Aron Super, magnesia was manufactured by Mitsui Metal Co., Ltd., trade name Mag Super, and molybdenum was a plate having a purity of 99.9% by weight and dimensions of 2 mm × 50 mm × 50 mm.

[0016]

[Table 1]

The sintered body was subjected to a tensile test, and tensile strength and elongation at break were measured. An analysis sample was cut out from the grip of the tensile test piece to measure the oxygen content. The results are also shown in Table 1.

Further, cracks were generated in Experiment Nos. 1 and 13 after the sintering treatment. In Experiment No. 15, 0.8% by weight of aluminum was detected in the sintered body. Experiment number 1
In No. 7, titanium and molybdenum reacted, and the sintered body and the setter were fixed. Experiment number 14 is 0.3 in the sintered body
Weight percent calcium was detected. Most of the present examples have an improved oxygen content compared to molybdenum (Experiment No. 17), and the ceramic of the present invention also has the effect of deoxidizing the sintered body.

[0019]

As described above, according to the present invention, CaO is 0.5 to 90% by weight and the balance is ZrO ₂ as a jig in the furnace.
By using the sintering ceramics consisting of and, the sintered body does not oxidize during the sintering process of the powder compact of titanium and titanium alloy, and the sintered body of titanium and titanium alloy with excellent mechanical properties is obtained. Obtainable.

Claims (2)

[Claims] 1. A molded body obtained by kneading, molding, and debinding a titanium or titanium alloy and a binder has a CaO value of 0.
A method for sintering titanium or a titanium alloy, which comprises placing the mixture on a ceramic containing 5 to 90% by weight and the balance ZrO ₂ , and optionally covering the ceramic with the ceramic for sintering. 2. CaO is 0.5 to 90% by weight and the balance is Z
Ceramics for sintering titanium or titanium alloys consisting of rO ₂ .