JPH0447021B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a decorative sintered alloy that has both decorative properties and corrosion resistance and is suitable for decorative parts such as watch exterior parts, tie pins, brooches, and fishing gear parts. Conventionally, materials for decorative items require corrosion resistance and scratch resistance, so WC, which is a hard alloy, has been used.
TaC-based, TaC-based, and TiC-based sintered alloys have been put into practical use. Among these, WC-based and TaC-based sintered alloys are expensive and have a high specific gravity, making them unsuitable for use as portable accessories, and WC-based and TiC-based sintered alloys have a monotonous black-gray color. The drawback is that it does not fully meet the requirements for decorative effects. To compensate for this drawback, coated alloys in which steel and sintered alloys are coated with TiN and/or TiC are used as decorative parts. However, coating alloys can be used for decorations because the color tone between the surface and inside of the coating layer may differ, the coating layer may peel off, and color tone unevenness may occur on the coating alloy surface due to changes in the quality and thickness of the coating layer that occur during the manufacturing process. The disadvantage is that it loses its value. Furthermore, many TiN-based colored sintered alloys have been proposed for decorative parts, but they have very poor sintering properties, and it is difficult to make alloys with poor sintering properties into a mirror-glossy surface. When used, there is a problem that defects on the mirror surface are noticeable, making it unsuitable for decorative parts. The decorative sintered alloy of the present invention solves the above-mentioned drawbacks and problems. In the process of sintering a compact consisting of TiN as a main raw material with a near stoichiometric composition and Fe group, when TiN dissolves in Fe group to form an Fe group solid solution, , since Ti and N cannot be dissolved in equimolar amounts in the Fe group, approximately 95% of nitrogen is discharged from the compact as N ₂ gas, so after the appearance of the liquid phase, this N ₂ gas remains and burns A phenomenon that inhibits the promotion of condensation occurs, and this decorative sintered alloy was obtained as a result of an investigation into preventing denitrification based on this phenomenon. The decorative sintered alloy of the present invention includes Fe, Ni, Co,
2 to 30% by weight of one or more binder phases selected from Cr, Mo, and W, 0.1 to 10% by weight of reinforcing phases consisting of metals, alloys, or compounds, and the remainder (Tia, Mb) (N _{W , C _}
indicates the atomic ratio of the metal corresponding to M, and a+b=
1, 1≧a≧0.4, 0.6≧b≧0, N is nitrogen, C is carbon, O is oxygen, W, X, Y are the atomic ratios of nitrogen, carbon, and oxygen, and Z is the nonmetallic constituent element relative to the metal. Indicates the ratio of W+X+Y=1, X+Y>0,
1>W≧0.4, 0.5≧X≧0, 0.6≧Y≧0.06, 0.93
≧Z≧0.6) and unavoidable impurities. The reinforcing phase in the decorative sintered alloy of the present invention is P, Al, B, Si, Mn, Ti, Zr, Hf, V,
In the case of one or more metals or alloys selected from Nb and Ta, it is said that during the sintering process, the temperature at which the liquid phase appears in the binder phase is lowered, promoting sinterability and improving the compactness of the sintered alloy. This contributes to the effect of bringing the binder phase into the state of an intermetallic compound or solid solution, thereby improving the strength, hardness, scratch resistance, and corrosion resistance of the sintered alloy. In addition, the reinforcing phase is one selected from AlN, Si ₃ N ₄ , BN, and Mo ₂ C.
In the case of more than one nitride, carbide, or a composite compound thereof, it acts to strengthen the grain boundaries and bond between the binder phase and the hard phase, thereby improving the strength, scratch resistance, and corrosion resistance of the sintered alloy. This contributes to the effectiveness. Furthermore, when the purpose is to improve the strength and hardness of the sintered body by dispersion strengthening in the binder phase, the reinforcing phase may be Al 2 O 3 , Al ₂ O ₃ ,
Contributing to improving the strength, scratch resistance, and corrosion resistance of the sintered body by using one or more oxides selected from Y ₂ O ₃ , ZrO ₂ , MgO, NiO, and SiO ₂ become. Furthermore, when the purpose is to strengthen the bond between the hard phase and the binder phase by strengthening the grain boundaries between the binder phase and the hard phase, the strengthening phase may be AlN, Si ₃ N ₄ , BN,
The use of one or more nitrides, carbides or composite compounds selected from Mo ₂ C contributes to improving the strength, scratch resistance and corrosion resistance of the sintered body. In the sintered alloy of the present invention, the denitrification that occurs during the process of sintering a green compact mainly composed of TiN has a non-stoichiometric composition, TiN _Z (0.95≧
Z≧0.6) Since the powder is used as a starting material, the N ₂ gas discharged outside the system reversely nitrides the TiNz powder, thereby preventing denitrification. or,
The addition of carbon and/or oxygen to _TiNz , such as Ti(N _{W , C} The strength and hardness of the sintered body increases, and the use of the reinforcing phase further increases the strength and hardness of the sintered body. A sintered alloy with excellent wear resistance, scratch resistance, and corrosion resistance. The decorative sintered alloy of the present invention maintains a golden yellow color tone due to the hard phase mainly composed of TiNz, but as the Z value becomes lower than the stoichiometric composition, the color tone changes from golden yellow to pale. TiO, ZrN, HfN, which changes to a golden color, and this color change becomes even more golden
By adding one or more of VN, NbN, TaN, CrN, Cr ₂ N, TaC, and NbC, it becomes easier to control the color and tone from a deep pale golden yellow to a clear golden yellow. The decorative sintered alloy of the present invention can be obtained by ordinary sintering in vacuum or in a non-oxidizing atmosphere, but it can be obtained by hot isostatic sintering (HIP). Furthermore, a denser and stronger sintered alloy can be obtained. Next, the reason for the numerical limitations in the decorative sintered alloy of the present invention will be described. In _the hard phase (Tia _, Mb) (N _W , _C It's also effective. In particular, CrN, ZrN, HfN, VN, NbN, which exhibits a golden color when metal M is compounded,
When adding one or more selected from TaN and Cr ₂ N, it is possible to select a wide range of mixing ratios between the atomic ratio a of Ti and the atomic ratio b of M, and this is limited. There is no essential reason, but it is necessary to consider lightweight and scratch resistance for portable use, and
When adding carbides such as ZrC, HfC, VC, _{Cr3C2 ,} etc., it is necessary to consider color and tone, so 1≧a≧0.4 and 0.6≧b≧0 are set. The nonmetallic elements N, C, and O are mainly composed of N in order to produce a golden-colored sintered alloy, and O (oxygen) is
When contained in a small amount, it helps to promote sinterability and improve scratch resistance, and when contained in a small amount, C (carbon) has similar effects. If the content of O and C is too large, the sinterability will decrease and the hardness of the sintered body will also decrease, so 1>W≧0.4, 0.5≧X≧0, 0.6≧
Y0.06 was set. Note that carbon C tends to have a stronger effect on promoting sinterability when added as free carbon than as carbon as a metal carbide. Z, which represents the ratio of nonmetallic elements to metallic elements, needs to be less than the stoichiometric composition in order to prevent outgassing and improve the hardness of the sintered body, but if it is too small, the compound may become defective. Since the dimensional accuracy of the sintered body decreases as it becomes more stable, it is determined that 0.93≧Z≧0.6. The amount of binder phase is related to the amount of hard phase and reinforcing phase,
Furthermore, it must be selected depending on the application, but if it is less than 2% by weight, the sinterability and density will decrease, and if it is less than 30% by weight,
The amount of the binder phase was determined to be from 2% by weight to 30% by weight, since if the amount exceeds 20% by weight, the hardness of the sintered body decreases and the scratch resistance deteriorates. The amount of reinforcing phase must be selected depending on the relationship with the amount of binder phase and the application, but if it is less than 0.1% by weight, it will have a weak effect on strengthening and improving the hardness of the sintered body.
If the amount exceeds 10% by weight, sinterability will deteriorate,
Since the sintered body also becomes brittle, the amount of reinforcing phase is 0.1% by weight.
10% by weight. The decorative sintered alloy of the present invention will be specifically described below based on examples. Example 1 TiNz, TiC, TiO, Ti(Nw, Cx)z, Ti(Nw, Oy)z, Ti(Nw, Cx, Oy)z, (Tia, Mb) Nz, (Tia, Mb) (Nw, Cx)z, (Tia, Mb) (Nw, Oy)z, (Tia, Mb)
(Nw, Cx, Oy)z, Various binder phase metals, reinforcing phases, and metal powder were blended in predetermined proportions, 2% paraffin was added as a lubricant, and then pulverized and mixed in a ball mill using an acetone solvent. The dried mixed powder was molded under a pressure of 2t/cm ² and heated at 1400°C to 1600°C in a vacuum of 10 ^-3 to ^{10 -4} mmHg.
After sintering at a temperature of 1100 °C in vacuum if necessary
Solution treatment was carried out at a temperature of 1250°C for 3 hours.
The sintered alloy thus obtained was mirror-polished using a diamond grindstone, and its mechanical properties, color tone, and corrosion resistance were examined. Mechanical properties measure hardness, resistance,
The corrosion resistance test was conducted by immersing each sample in artificial seawater and artificial sweat at 50°C for 7 days and then observing the mirror surface of the sample. The composition, sintering conditions and solution treatment conditions of each sample are shown in Table 1, and the hard phase structure, binder phase, transverse rupture strength, hardness, color tone and artificial seawater of each sample after sintering and solution treatment Corrosion resistance due to artificial sweat was investigated, and the results are shown in Table 2.

【table】

【table】

[Table] Example 2 Each powder of Al ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , MgO, NiO, SiO ₂ and each raw material powder used in Example 1 were mixed in a predetermined ratio, and the Each sample was sintered using the same manufacturing method as in Example 1 and tested for mechanical properties, color tone, and corrosion resistance. The composition, sintering conditions, and solution treatment conditions of each sample are shown in Table 3, and the structure, bonding phase, reinforcing phase, transverse rupture strength, hardness, and color tone of the hard phase of each sample after sintering and solution treatment. The corrosion resistance caused by artificial seawater and artificial sweat was also investigated, and the results are shown in Table 4.

【table】

[Table] Example 3 Each powder of AlN, Si ₃ N ₄ , BN, Mo ₂ C and each raw material powder used in Example 1 were mixed in a predetermined ratio, and the same manufacturing method as in Example 1 was used. After sintering, the mechanical properties, color tone, and corrosion resistance of each sample were tested. Table 5 shows the composition, sintering conditions, and solution treatment conditions of each sample. Corrosion resistance due to artificial seawater and artificial sweat was investigated, and the results are shown in Table 6.

【table】

【table】

[Table] Example 4 Samples No. 1, 7, and 12 sintered in Example 1, Samples No. 14, 17 sintered in Example 2, and Samples No. 19, 21, and sintered in Example 3. After HIPing each of the 26 samples at 1500bar-1350℃, mechanical properties, color tone and corrosion resistance tests were conducted. The results of these tests are shown in Table 7.

【table】

【table】

Claims (1)

[Claims] 1. 2 to 30% by weight of one or more binder phases selected from Fe, Ni, Co, Cr, Mo, and W, and P, Al,
One or more metals or alloys of B, Si, Mn, Ti, Zr, Hf, V, Nb, Ta or Al, Y, Zr, Mg, Ni, Si
0.1 to 10% by weight of a reinforcing phase consisting of oxides of Al, Si, B nitrides, carbides of Mo, or compounds of one or more of these mutual solid solutions, and the remainder is a hard phase represented by the following formula (A). A decorative sintered alloy characterized by comprising: and inevitable impurities. (Tia _, Mb ₎ (N _{W ,} C a≧0.4, 0.6≧b≧0 W + X + Y = 1, X + Y > 0, 1 > W ≧ 0.4 0.5 ≧ Si, Mn, Ti,
The decorative sintered alloy according to claim 1, characterized in that it is one or more single metals or alloys selected from Zr, Hf, V, Nb, and Ta. 3 The above reinforcing phase is Al ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , MgO,
The decorative sintered alloy according to claim 1 or 2, characterized in that it is one or more oxides selected from NiO and SiO ₂ . 4. Claim 1 or 4, wherein the reinforcing phase is one or more nitrides, carbides, or composites selected from AlN, Si ₃ N ₄ , BN, Mo ₂ C. Decorative sintered alloy according to item 2.