CN1313367C - Fine granule Cr3C2 preparation method - Google Patents

Abstract

The present invention provides a preparation method for Cr3 C2 powder which can satisfy that fisher particle size Fsss for superfine hard alloy production is equal to or less than 2 mu m. The present invention orderly comprises the following steps that when a stainless steel container is heated to 300 DEG C to 350 DEG C, temperature rise is stopped, ammonium dichromate powder is added into the container at intervals for decomposition, feed is stopped after 2 to 4 hours, and Cr2 O3 of 20 to 40 nanometers is obtained through discharge after the stainless steel container is cooled to room temperature; Cr2 O3 and C aggregate are mixed according to the weight ratio of C to Cr2 O3 of 0.32 to 0.35; the uniformly mixed Cr2 O3 and C are added into a vacuum furnace for carbonization, the vacuum degree is less than 10Pa, after the temperature rises to 1150 to 1200 DEG C, the temperature is kept for 11 to 13 hours, and H2 is fed to cool the temperature to the room temperature; the Cr3 C2 powder is obtained and crushed by ball milling to obtain the Cr3 C2 powder with complete carbonation, and the Fsss of the Cr3 C2 powder is equal to or less than 2 mu m. The present invention has the advantages of combination of chemical decomposition and vacuum melting, low carbonization temperature, short time and low cost.

Description

Fine grained Cr 3C 2The preparation method

Technical field

The present invention relates to fine grained Cr ₃C ₂The preparation method, relate in particular to the method that adopts chemical breakdown to combine with vacuum metling and produce fine grained Cr ₃C ₂Powder.

Background technology

Cr ₃C ₂Grain growth inhibitor as carbide alloy is widely used, development along with electronics industry, requirement to ultra-fine cemented carbide is more and more higher, as the granularity of the principal phase WC of ultra-fine cemented carbide generally below 0.8 μ m, thereby to also more and more higher as the granularity requirements of carbide alloy additive.

Preparation Cr ₃C ₂The conventional method of powder is with common Cr ₂O ₃Mix with the solid carbon ball milling, the carbonization of carbon shirt-circuiting furnace secondary forms, the method carburizing temperature is higher, generally needs 1400～1500 ℃, carbonization time longer, powder size is generally about 3～5 μ m, is difficult to satisfy ultra-fine cemented carbide to the requirement of inhibitor.

Both at home and abroad to preparation fine grained Cr ₃C ₂Report less, also mainly concentrate on gas carburization, utilize the carbonization Cr of organic substance decomposing ₂O ₃Preparation Cr ₃C ₂, all there is the cost height in these methods, are difficult to realize the shortcomings such as industrialization.

Summary of the invention

The present invention is directed to above-mentioned deficiency, a kind of Cr that can satisfy ultra-fine cemented carbide production Fisher particle size Fsss≤2 μ m is provided ₃C ₂The preparation method of powder adopts chemical breakdown to combine with vacuum metling, and carburizing temperature is low, the time is short, and cost is low.

Fine grained Cr of the present invention ₃C ₂The preparation method, may further comprise the steps successively:

Stop when (1) the open type rustless steel container being heated to 300 ℃～350 ℃ heating up, adding an ammonium dichromate powder in the clockwise container every 0.5～1 minute decomposes, feeding quantity is 200～300 grams, stop to feed in raw material after 2～4 hours, after treating the rustless steel container cool to room temperature, discharging obtains the Cr of 20～40 nanometers ₂O ₃;

(2) with above-mentioned Cr ₂O ₃Add up to 20～50Kg to carry out 1～3 hour mixing with C, wherein wt compares C:Cr ₂O ₃=0.32～0.35;

(3) with mixed uniformly Cr ₂O ₃Add vacuum drying oven with C and carry out carbonization, vacuum＜10Pa, batch is 20～25 kilograms/stove, temperature reaches 1150～1200 ℃, is incubated after 11～13 hours, logical H ₂Cool off 12～15 hours to room temperature, obtain Cr ₃C ₂Powder;

(4) will obtain Cr ₃C ₂Powder ball mill crushing 6～8 hours, the Cr of the C content 12.8～13.5% that obtains ₃C ₂Powder, its granularity≤2 μ m.

Ultimate principle of the present invention is:

(1)

(2)

The present invention utilizes bursting apart of ammonium dichromate thermal decomposition and very exothermic, obtains nanometer Cr ₂O ₃, make the carbonized stock refinement; Nano level Cr ₂O ₃Mix when reacting with C, because the tiny reaction diffusion length that makes of feed particles shortens, carburizing temperature is reduced, effectively stop Cr ₃C ₂Growing up of crystal grain; The CO gas that generates during simultaneously owing to vacuum carburization constantly is pumped, impel reaction to carry out to the right, also make reaction temperature lower, thereby fully (C 〉=12.8% of carbonization is prepared in the carbonization of realization vacuum and low temperature, 0≤0.6%, percentage by weight) and the fine grained Cr of granularity≤2 μ m ₃C ₂Powder.The inventive method carbonization temperature is low, the time short, and easy to operate, cost is low.

Embodiment

Embodiment 1: cutting off the electricity supply when stainless cylinder of steel is heated to 300 ℃ stops to heat up, in tank, add ammonium dichromate, the rapid decomposition caused heat release of ammonium dichromate also produces gas, each addition is 280 grams, adds a defective material, and decomposes after 2 hours in per 0.5 minute, stop to feed in raw material, with water cooling stainless steel tank, treat discharging behind the stainless cylinder of steel cool to room temperature, the Cr that obtains ₂O ₃Powder is 36 sodium rice by its granularity of nitrogen adsorption method (following examples together), and weight is 22.4 kilograms, by weight C:Cr ₂O ₃=0.335 joins carbon, batch mixing 2 hours, and vacuum drying oven is advanced in discharging.Vacuum tightness is 5Pa, and being warmed up to 1180 ℃ of soaking times is 11 hours.Logical H ₂Cooling, be 12 hours cool time.Ball milling is 6 hours after the discharging.Sampling and measuring sees Table 1, and its granularity is 1.42 μ m, C=13.24% by weight, and O=0.35%, carbonization is complete, and chemical ingredients meets the requirements.

Embodiment 2: cutting off the electricity supply when stainless cylinder of steel is heated to 330 ℃ stops to heat up, in tank, add ammonium dichromate, the rapid decomposition caused heat release of ammonium dichromate also produces gas, each addition is 300 grams, adds a defective material, and decomposes after 2.5 hours in per 1 minute, stop to feed in raw material, with water cooling stainless steel tank, treat the rear discharging of stainless cylinder of steel cooling, the Cr that obtains ₂O ₃Powder Particle Size is 25 sodium rice, and weight is 20 kilograms, by weight C:Cr ₂O ₃=0.342 joins carbon, batch mixing 1 hour, and vacuum drying oven is advanced in discharging.Vacuum tightness is 6Pa, is warmed up to 1160 ℃, and soaking time is 11 hours.Logical H ₂Cooling, be 12 hours cool time.Ball milling is 6 hours after the discharging.Sampling and measuring sees Table 1, and its granularity is 1.31 μ m, C=13.36% by weight, and O=0.36%, carbonization is complete, and chemical ingredients meets the requirements.

Embodiment 3: cutting off the electricity supply when stainless cylinder of steel is heated to 340 ℃ stops to heat up, in tank, add ammonium dichromate, the rapid decomposition caused heat release of ammonium dichromate also produces gas, each addition is 290 grams, adds a defective material, and decomposes after 3.5 hours in per 1 minute, stop to feed in raw material, with water cooling stainless steel tank, treat the rear discharging of stainless cylinder of steel cooling, the Cr that obtains ₂O ₃Powder Particle Size is 34 sodium rice, and weight is 38.9 kilograms, by weight C:Cr ₂O ₃=0.345 joins carbon, batch mixing 3 hours, and vacuum drying oven is advanced in discharging.Two batches of shove charges, vacuum tightness is 8Pa, being warmed up to 1190 ℃ of soaking times is 12 hours.Logical H ₂Cooling, be 14 hours cool time.Ball milling is 7 hours after the discharging.Sampling and measuring sees Table 1, and its granularity is 1.65 μ m, C=13.35% by weight, and O=0.21%, carbonization is complete, and chemical ingredients meets the requirements.

Embodiment 4: cutting off the electricity supply when stainless cylinder of steel is heated to 350 ℃ stops to heat up, in tank, add ammonium dichromate, the rapid decomposition caused heat release of ammonium dichromate also produces gas, each addition is 300 grams, adds a defective material, and decomposes after 4 hours in per 1 minute, stop to feed in raw material, with water cooling stainless steel tank, treat the rear discharging of stainless cylinder of steel cooling, the Cr that obtains ₂O ₃Powder Particle Size is 29 sodium rice, and weight is 46.0 kilograms, by weight C:Cr ₂O ₃=0.350 joins carbon, batch mixing 3 hours, and vacuum drying oven is advanced in discharging.Vacuum tightness is 10Pa, and being warmed up to 1200 ℃ of soaking times is 13 hours.Logical H ₂Cooling, be 15 hours cool time.Ball milling is 8 hours after the discharging.Sampling and measuring sees Table 1, and its granularity is 1.42 μ m, C=13.42% by weight, and O=0.23%, carbonization is complete, and chemical ingredients meets the requirements.

Table 1: the chemical ingredients of fine particle Cr3C2

Lot number	C	O	N	Ca	Al	Fe	Mo	Na	Si	Fsss(μm)
											Embodiment 1 embodiment 2 embodiment 3 embodiment 4	13.24 13.36 13.35 13.42	0.35 0.36 0.21 0.23	0.023 ＜0.1 0.012 0.010	＜0.01 ＜0.01 ＜0.01 ＜0.01	＜0.01 ＜0.01 ＜0.01 ＜0.01	0.063 0.025 0.034 0.025	＜0.01 ＜0.01 ＜0.01 ＜0.01	＜0.01 ＜0.01 ＜0.01 ＜0.01	＜0.01 ＜0.01 ＜0.01 ＜0.01	1.42 1.31 1.65 1.42

Claims (1)

1, a kind of fine grained Cr ₃C ₂The preparation method, may further comprise the steps successively:

Stop when (1) the open type rustless steel container being heated to 300 ℃～350 ℃ heating up, adding an ammonium dichromate powder in the clockwise container every 0.5～1 minute decomposes, feeding quantity is 200～300 grams, stop to feed in raw material after 2～4 hours, after treating the rustless steel container cool to room temperature, discharging obtains the Cr of 20～40 nanometers ₂O ₃;

(2) with above-mentioned Cr ₂O ₃Add up to 20～50Kg to carry out 1～3 hour mixing with C, wherein wt is than C: Cr ₂O ₃=0.32～0.35;

(3) with mixed uniformly Cr ₂O ₃Add vacuum drying oven with C and carry out carbonization, vacuum＜10Pa, batch is 20～25 kilograms/stove, temperature reaches 1150～1200 ℃, is incubated after 11～13 hours, logical H ₂Cool off 12～15 hours to room temperature, obtain Cr ₃C ₂Powder;

(4) will obtain Cr ₃C ₂Powder ball mill crushing 6～8 hours, the Cr of the C content 12.8～13.5% that obtains ₃C ₂Powder, its granularity≤2 μ m.