A method for short process preparation of low interstitial impurity hydrogenated pre-alloyed powder

Abstract

The application belongs to the technical field of hydrogenated pre-alloy powder preparation, and particularly relates to a short-process method for preparing low-gap-impurity hydrogenated pre-alloy powder, which comprises the following steps: S1: mixing hydrogenated titanium powder, alloy powder and / or ceramic powder according to a preset ratio to obtain mixed powder; S2: adding ammonium bicarbonate particles to the mixed powder and uniformly mixing; S3: performing die pressing or cold isostatic pressing on the composite powder obtained in step S2 to obtain a powder compact; S4: performing vacuum sintering on the powder compact at a temperature increasing rate of 5-20 DEG C / min, keeping at 100-150 DEG C for 0.5-1 h, keeping at 1200-1400 DEG C for 2-4 h, and cooling in the furnace; S5: when the furnace temperature drops to 500-700 DEG C, high-purity hydrogen is introduced into the furnace and kept for 1-2 h, and the furnace is cooled to room temperature; and S6: mechanically crushing the obtained hydrogenated pre-alloy block under argon protection and performing screening to obtain hydrogenated pre-alloy powder with a required particle size. The application greatly shortens the process window temperature and time of hydrogenation and reduces the difficulty of mechanical crushing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogenation pre-alloy powder preparation, and particularly relates to a short-process method for preparing low-interstitial impurity hydrogenation pre-alloy powder. BACKGROUND

[0002] Titanium alloy, as a high-performance, corrosion-resistant and heat-resistant metal structural material, is widely used in the fields of aviation, aerospace, medical treatment and the like. However, the manufacturing of titanium alloy needs to go through multiple processes and complex processing procedures, including smelting, casting, forging, heat treatment and the like. These processes not only have high technical requirements, but also need precise equipment and process, and therefore the production cost is relatively high.

[0003] Researches show that the mixed element powder metallurgy method based on titanium hydride (TiH2) can fully utilize the advantages of near-net forming of the powder metallurgy method and the characteristics of low cost and brittleness of titanium hydride, and greatly reduce the preparation cost of titanium alloy. However, the pressing-sintering characteristics of different powder particles are different, and the melting points and diffusion rates among elements are greatly different, which leads to the problems of a large number of residual pores in the sintered structure and poor composition uniformity. The use of hydrogenation pre-alloy powder instead of alloy powder mixed with TiH2 to prepare hydride composite powder can significantly improve the composition uniformity and density of titanium alloy / titanium-based composite material. The hydrogen-induced brittleness and volume shrinkage during the dehydrogenation process make the hydrogenation pre-alloy particles and TiH2 always keep close combination, which ensures the smooth progress of the interface element diffusion process and the pore healing process. However, the hydrogenation pre-alloy powder prepared by pre-sintering-hydrogenation-crushing-secondary sintering has the problems of low hydrogen absorption efficiency, great crushing difficulty and high impurity content, which seriously affects the efficiency of the process flow and the performance of the prepared material. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a short-process method for preparing low-interstitial impurity hydrogenation pre-alloy powder in view of the deficiencies in the prior art. The method is prepared by mixing ammonium bicarbonate and titanium hydride to obtain a sponge-like porous structure sintered blank, and then hydrogenating, crushing and screening the sintered blank. The material is not completely dehydrogenated by quickly passing through the dehydrogenation temperature range, which speeds up the high-temperature pre-alloying process and reduces the hydrogenation-crushing time.

[0005] The present application is realized by the following technical measures: a short-process method for preparing low-interstitial impurity hydrogenation pre-alloy powder, which comprises the following steps:

[0006] S1: uniformly mixing titanium hydride powder, alloy powder and / or ceramic powder in a preset proportion under argon protection for 4-8 hours to obtain a mixed powder;

[0007] S2: adding ammonium bicarbonate particles to the mixed powder obtained in step S1 and uniformly mixing under argon protection for 1-2 hours to obtain a composite powder;

[0008] S3: The composite powder obtained in step S2 is molded or cold isostatically pressed at 300-600 MPa to obtain a powder blank;

[0009] S4: Place the powder blank in a sintering furnace and vacuum sinter it at a heating rate of 5-20℃ / min. Hold it at 100-150℃ for 0.5h-1h to remove ammonium bicarbonate, and hold it at 1200-1400℃ for 2-4h to complete pre-alloying. Then cool it with the furnace.

[0010] S5: When the furnace temperature drops to 500-700℃, high-purity hydrogen is introduced into the furnace and kept at that temperature for 1-2 hours, then the furnace is cooled to room temperature.

[0011] S6: The obtained hydrogenated pre-alloyed block is mechanically crushed and sieved under argon protection to obtain hydrogenated pre-alloyed powder of the desired particle size.

[0012] Preferably, the particle size of the ammonium bicarbonate particles in step S2 is 0.5-2 mm.

[0013] Preferably, in the mixed powder of step S1, titanium hydride powder accounts for ≥30% by mass fraction.

[0014] Preferably, in the composite powder of step S2, ammonium bicarbonate particles account for 20-80% by mass fraction.

[0015] Preferably, in the composite powder of step S2, the mass fraction of ammonium bicarbonate particles is equal to the mass fraction of the mixed powder obtained in step S1.

[0016] Preferably, the mixed powder obtained in step S1 is obtained by mixing TiH2 with a particle size of less than 88 μm, ZrH2 with a particle size of less than 45 μm, and Nb powder with a particle size of less than 63 μm in a mass ratio of 1:1:1.

[0017] Preferably, the mixed powder obtained in step S1 is obtained by mixing TiH2 with a particle size of less than 88 μm, TiB2 with a particle size of less than 10 μm, and Al-V powder with a particle size of less than 63 μm in a mass ratio of 90:6:10.

[0018] Preferably, the particle size of the hydrogenated pre-alloyed powder in step S6 is less than 45 μm.

[0019] The present application has the following beneficial effects: the present application introduces ammonium bicarbonate and titanium hydride into the powder compact to jointly act, and the preparation of the pre-alloyed compact with a sponge-like porous structure is completed through integrated pressing and vacuum sintering; the increase of the specific surface area and the incomplete dehydrogenation of the pre-alloyed compact not only accelerate the pre-alloying process, but also greatly shorten the process window temperature and time of hydrogenation and reduce the difficulty of mechanical crushing. After hydrogenation, mechanical crushing and screening, the low-interstitial impurity high-quality hydrogenated pre-alloyed powder is prepared at a low cost. Therefore, compared with the prior art, the present application has outstanding substantial characteristics and significant progress, and the beneficial effects of the implementation are also obvious. DETAILED DESCRIPTION

[0020] In order to clearly illustrate the technical features of the present application, the present application will be described below through specific embodiments.

[0021] A short-process method for preparing low-interstitial impurity hydrogenated pre-alloyed powder, which comprises the following steps:

[0022] S1: uniformly mixing titanium hydride powder, alloy powder and / or ceramic powder in a preset ratio under argon protection for 4-8h to obtain a mixed powder, wherein the mass fraction of the titanium hydride powder in the mixed powder is ≥30%;

[0023] S2: adding ammonium bicarbonate particles to the mixed powder obtained in step S1, wherein the particle size of the ammonium bicarbonate particles is 0.5-2mm, and uniformly mixing the mixed powder and the ammonium bicarbonate particles under argon protection for 1-2h to obtain a composite powder, wherein the mass fraction of the ammonium bicarbonate particles in the composite powder is 20-80%, and preferably the mass fraction of the ammonium bicarbonate particles is equal to the mass fraction of the mixed powder obtained in step S1; the large-particle ammonium bicarbonate with a particle size greater than 0.5mm can avoid the problem that the small-particle ammonium bicarbonate increases the small pores in the compact, affects the mutual contact area between the main element particles, and restricts the element diffusion and mass exchange at the high-temperature stage, and at the same time, the large-particle ammonium bicarbonate can avoid the problem of affecting element diffusion and realize the formation of the porous structure inside and on the surface of the compact, so that the specific surface area of the compact is greatly increased, the hydrogenation effect is better during hydrogenation, the hydrogenation time is shorter, and oxygen control is facilitated;

[0024] S3: obtaining a compact by die pressing or cold isostatic pressing the composite powder obtained in step S2 at 300-600Mpa;

[0025] S4: placing the compact in a sintering furnace and performing vacuum sintering at a heating rate of 5-20℃ / min, wherein the temperature is kept at 100-150℃ for 0.5h-1h to remove the ammonium bicarbonate, the temperature is kept at 1200-1400℃ for 2-4h to complete pre-alloying, and the furnace is cooled down;

[0026] S5: When the hearth temperature drops to 500-700℃, high-purity hydrogen is introduced into the furnace and kept for 1-2h, and the furnace is cooled to room temperature;

[0027] S6: The obtained hydrogenated pre-alloy block is mechanically broken and sieved under argon protection to obtain a hydrogenated pre-alloy powder with a desired particle size.

[0028] The application will be further described in detail below through specific examples.

[0029] Example 1

[0030] Preparation of (Ti-Nb-Zr)Hx hydrogenated pre-alloy powder

[0031] S1: TiH2 with a particle size less than 88um, ZrH2 with a particle size less than 45um and Nb powder with a particle size less than 63um are placed in a mixing bottle in a mass ratio of 1:1:1 and uniformly mixed for 4h under argon protection to obtain a mixed powder;

[0032] S2: Ammonium bicarbonate particles with a particle size of 0.8mm are added to the mixed powder in the mixing bottle in an amount equal to the mass fraction of the mixed powder, and the mixed powder is uniformly mixed for 1h under argon protection to obtain a composite powder;

[0033] S3: The composite powder obtained in step S2 is die pressed at 600Mpa to obtain a 10*10*60mm rectangular powder compact;

[0034] S4: The powder compact is placed in a sintering furnace and vacuum sintered at a heating rate of 10℃ / min, wherein, ammonium bicarbonate is removed by keeping at 100℃ for 0.5h, and pre-alloying is completed by keeping at 1300℃ for 2h, and the furnace is cooled;

[0035] S5: When the hearth temperature drops to 600℃, high-purity hydrogen is introduced into the furnace to keep the hydrogen partial pressure at 50Kpa and kept for 1h, and the furnace is cooled to room temperature;

[0036] S6: The obtained hydrogenated pre-alloy block is mechanically broken and sieved under argon protection to obtain a (Ti-Nb-Zr)Hx hydrogenated pre-alloy powder with a particle size less than 45um (O content about 2100ppm; N content about 300ppm; H content about 5100ppm).

[0037] Comparative Example 1

[0038] Preparation of (Ti-Nb-Zr)Hx hydrogenated pre-alloy powder

[0039] S1: Ti with a particle size less than 88um, ZrH2 with a particle size less than 45um and Nb powder with a particle size less than 63um are placed in a mixing bottle in a mass ratio of 1:1:1 and uniformly mixed for 4h under argon protection;

[0040] S2: The mixed powder obtained in step S1 was die pressed at 600 MPa to obtain a 10*10*60 mm rectangular powder compact;

[0041] S3: The powder compact was placed in a sintering furnace and vacuum sintered at a heating rate of 10°C / min, wherein, after holding at 1300°C for 2 h, the furnace was cooled down;

[0042] S4: After the furnace temperature dropped to 600°C, high-purity hydrogen was introduced into the furnace to maintain a hydrogen partial pressure of 50 KPa and hold for 1 h, and the furnace was cooled to room temperature;

[0043] S5: The obtained hydrogenated pre-alloy bulk body was mechanically broken and sieved under argon protection, and finally (Ti-Nb-Zr)Hx hydrogenated pre-alloy powder with a particle size of less than 45 um (O content of about 3500 ppm; N content of about 800 ppm; H content of about 2300 ppm) was obtained.

[0044] Example 2

[0045] Preparation of (TC4-10%TiB)Hx hydrogenated pre-alloy powder

[0046] S1: TiH2 with a particle size of less than 88 um, TiB2 with a particle size of less than 10 um, and Al-V powder with a particle size of less than 63 um were placed in a mixing bottle in a mass ratio of 90:6:10 and uniformly mixed under argon protection for 6 h to obtain a mixed powder;

[0047] S2: Ammonium bicarbonate particles with a particle size of 1 mm were added to the mixed powder in the mixing bottle in an amount equal to the mass fraction of the mixed powder, and the mixed powder was uniformly mixed under argon protection for 1 h to obtain a composite powder;

[0048] S3: The composite powder obtained in step S2 was cold isostatic pressed at 600 MPa to obtain a φ20*80 mm cylindrical powder compact;

[0049] S4: The powder compact was placed in a sintering furnace and vacuum sintered at a heating rate of 10°C / min, wherein, after holding at 150°C for 0.5 h to remove ammonium bicarbonate, holding at 1200°C for 2 h to complete pre-alloying, and cooling the furnace;

[0050] S5: After the furnace temperature dropped to 550°C, high-purity hydrogen was introduced into the furnace and held for 1 h, and then the furnace was cooled to room temperature;

[0051] S6: The obtained hydrogenated pre-alloy bulk body was mechanically broken and sieved under argon protection, and finally (TC4-10%TiB)Hx hydrogenated pre-alloy powder with a particle size of less than 45 um (O content of about 2400 ppm; N content of about 400 ppm; H content of about 4500 ppm) was obtained.

[0052] Comparative Example 2

[0053] Preparation of (TC4-10%TiB)Hx hydrogenated pre-alloy powder

[0054] S1: Ti with a particle size less than 88 um, TiB2 with a particle size less than 10 um and Al-V powder with a particle size less than 63 um were placed in a mixing bottle in a mass ratio of 90:6:10 and uniformly mixed for 6 h under argon protection;

[0055] S2: the mixed powder obtained in step S1 was cold isostatic pressed at 600 Mpa to obtain a φ20*80 mm cylindrical powder compact;

[0056] S3: the powder compact was placed in a sintering furnace and vacuum sintered at a heating rate of 10 ℃ / min, wherein, after holding at 1200 ℃ for 2 h, the furnace was cooled;

[0057] S4: when the furnace temperature dropped to 550 ℃, high-purity hydrogen was introduced into the furnace and held for 1 h, and then the furnace was cooled to room temperature;

[0058] S5: the obtained hydrogenated pre-alloy block was mechanically broken and sieved under argon protection, and finally (TC4-10%TiB)Hx hydrogenated pre-alloy powder with a particle size less than 45 um (O content about 3800 ppm; N content about 850 ppm; H content about 2700 ppm) was obtained.

[0059] From Examples 1-2 and Comparative Examples 1-2, it can be seen that the evaporation and decomposition of the large particle ammonium bicarbonate introduced in the powder compact during the sintering process forms a large number of pores in the interior and surface of the powder compact, greatly increasing the specific surface area of the material, and the hydrogenation effect of the material is obviously improved. The brittle main alloy hydrogenated powder introduced in the present application makes the powder compact pressed to form a more dense powder compact, promoting the formation of a more compact combination between different particles; the incomplete dehydrogenation during the sintering process (not holding at a dehydrogenation temperature interval alone) makes a large number of H atoms exist in the crystal lattice, not only effectively accelerating the element diffusion process in the high-temperature sintering stage, but also reducing the time required for hydrogenation.

[0060] The technical features not described in the present application can be realized by the prior art, which will not be described here. The present application is not limited to the above specific embodiments, and changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present application should also be within the scope of the present application.

Claims

1. A short-process method for preparing low-interstitial-impurity hydrogenated pre-alloyed powder, characterized in that, It includes the following steps: S1: Mix titanium hydride powder with alloy powder and / or ceramic powder in a preset ratio under argon protection for 4-8 hours to obtain mixed powder; S2: Add ammonium bicarbonate particles to the mixed powder obtained in step S1, and mix evenly for 1-2 hours under argon protection to obtain composite powder; S3: The composite powder obtained in step S2 is molded or cold isostatically pressed at 300-600 MPa to obtain a powder blank; S4: Place the powder blank in a sintering furnace and vacuum sinter it at a heating rate of 5-20℃ / min. Hold it at 100-150℃ for 0.5h-1h to remove ammonium bicarbonate, and hold it at 1200-1400℃ for 2-4h to complete pre-alloying. Then cool it with the furnace. S5: When the furnace temperature drops to 500-700℃, high-purity hydrogen is introduced into the furnace and kept at that temperature for 1-2 hours, then the furnace is cooled to room temperature. S6: The obtained hydrogenated pre-alloyed block is mechanically crushed and sieved under argon protection to obtain hydrogenated pre-alloyed powder of the desired particle size.

2. The method for preparing low-gap impurity hydrogenated pre-alloyed powder using a short-process method according to claim 1, characterized in that, The particle size of the ammonium bicarbonate particles in step S2 is 0.5-2 mm.

3. The method for preparing low-gap impurity hydrogenated pre-alloyed powder using a short-process method according to claim 2, characterized in that, In the mixed powder of step S1, the mass fraction of titanium hydride powder is ≥30%.

4. The method for preparing low-gap impurity hydrogenated pre-alloyed powder using a short-process method according to claim 3, characterized in that, In the composite powder of step S2, ammonium bicarbonate particles account for 20-80% by mass fraction.

5. The method for preparing low-gap impurity hydrogenated pre-alloyed powder using a short-process method according to claim 4, characterized in that, In the composite powder of step S2, the mass fraction of ammonium bicarbonate particles is equal to the mass fraction of the mixed powder obtained in step S1.

6. The method for preparing low-gap impurity hydrogenated pre-alloyed powder using a short-process method according to claim 5, characterized in that, The mixed powder obtained in step S1 is a mixture of TiH2 with a particle size of less than 88 μm, ZrH2 with a particle size of less than 45 μm, and Nb powder with a particle size of less than 63 μm in a mass ratio of 1:1:

1.

7. The method for preparing low-gap impurity hydrogenated pre-alloyed powder using a short-process method according to claim 5, characterized in that, The mixed powder obtained in step S1 is a mixture of TiH2 with a particle size of less than 88 μm, TiB2 with a particle size of less than 10 μm, and Al-V powder with a particle size of less than 63 μm in a mass ratio of 90:6:

10.

8. The method for preparing low-interval-impurity hydrogenated pre-alloyed powder using a short-process method according to claim 7, characterized in that, In step S6, the particle size of the hydrogenated pre-alloyed powder is less than 45 μm.