CN103451462B - A kind of rare earth improves block Cr 7c 3the method of anti-erosion performance - Google Patents

Abstract

The invention discloses a kind of rare earth and improve block Cr ₇c ₃the method of anti-erosion performance, the method utilizes Cr powder and Graphite Powder 99 and rare-earth yttrium block material, by controlling suitable ball-milling technology and sintering schedule, successfully can prepare the Cr after doped yttrium ₇c ₃compound, makes its toughness and antioxidant property significantly improve.Cr prepared by the present invention ₇c ₃after doped with yttrium element, its toughness improves 0.6-1.5 doubly, and at 1000 DEG C, under high temperature oxidative atmosphere, wear resistance improves more than about 1.8 times.

Description

A method for improving the anti-abrasion performance of bulk Cr7C3 by rare earth

technical field

The invention belongs to the technical field of anti-corrosion compounds, and relates to a method for improving the anti-corrosion performance of Cr ₇ C ₃ blocks, in particular to a method for improving the anti-corrosion performance of Cr ₇ C ₃ blocks with rare earth.

Background technique

Although bulk Cr ₇ C ₃ has excellent high temperature oxidation resistance without wear, under the interaction of wear and oxidation, due to the combination of dense Cr ₂ O ₃ oxide film on the surface and Cr ₇ C ₃ The ability is obviously insufficient, which is not conducive to the improvement of the corrosion resistance of Cr ₇ C ₃ . In the process of preparing bulk Cr ₇ C ₃ , the density of Cr ₂ O ₃ oxide film can be further improved by doping an appropriate amount of rare earth yttrium element, and at the same time, the bonding ability of oxide and Cr ₇ C ₃ body will be significantly improved. At the same time, due to the doping of an appropriate amount of rare earth element yttrium in the Cr ₇ C ₃ lattice, some crystal planes in Cr ₇ C ₃ such as (010) will change from the original covalent bond to the metal bond (this has been passed in the previous stage. proved by theoretical calculations). The toughness will be significantly improved under the condition that its own hardness will hardly decrease. During the wear process, it is obvious that it is not easy to crack and fall off to improve its wear resistance. To sum up, this undoubtedly has important engineering application significance for improving the high temperature oxidation resistance and wear resistance of Cr ₇ C ₃ .

In addition, based on the calculation of the first performance principle of density functional theory, it can be known that the Gibbs free energy of rare earth element yttrium dissolving in Cr ₇ C ₃ is about -91.6J/mol; and by calculating (Cr, Y) ₇ C ₃ The thermodynamic enthalpy change value formed is negative, further indicating that the compound is a stable structure. In conclusion, it is completely feasible to prepare (Cr, Y) ₇ C ₃ from the perspective of thermodynamic theory. It will have important engineering application value to use the block material on parts such as high-temperature wear-resistant guide plate for hot-rolled steel.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcoming of prior art, provide a kind of method that rare earth improves the anti-abrasion performance of block Cr ₇ C ₃ , this method utilizes rare earth yttrium to improve Cr ₇ C ₃ compound, by controlling ball milling process and sintering system , the yttrium-doped Cr ₇ C3 carbide can be successfully prepared, and its toughness and oxidation resistance can be significantly improved.

The purpose of the present invention is achieved through the following technical solutions:

The method for improving the anti-abrasion performance of bulk Cr ₇ C ₃ by rare earth comprises the following steps:

1) Crush the rare earth yttrium block to a particle size of less than 200 μm, and perform ball milling under vacuum argon filling. When the particle size is 20-30 μm, stop the machine and store the rare earth yttrium powder in a vacuum;

2) Convert the pure Cr powder and graphite powder into the weight ratio according to the atomic ratio in the molecular formula of carbide Cr ₇ C ₃ and the atomic weight of each element and weigh them respectively. Vacuum and ball mill for 10-20 hours;

3) 2-3 hours after stopping the ball mill, add the ball milled rare earth yttrium powder into the ball mill tank filled with evenly mixed Cr powder and graphite powder. The amount of rare earth yttrium powder added is 0.05% of the total weight of Cr powder and graphite powder. -1.0%, vacuumize again and turn on the ball mill, and ball mill for 30-50 hours. After the ball mill is completed, quickly fill the mixture of rare earth yttrium powder, Cr powder and graphite powder into the mold;

4) Put the graphite mold containing the mixture of rare earth yttrium powder, Cr powder and graphite powder into a sintering furnace for sintering. The sintering is carried out in a vacuum hot-pressing sintering furnace. The vacuum degree of the vacuum furnace during sintering is: ≤10 ^{- 1} Pa; the heating rate of the sintering furnace is: 5-10°C/s; the pressure is: 30-50MPa; the sintering temperature is: 1000°C-1400°C; the holding time is: 60-120 minutes. After cooling, the rare earth-improved bulk Cr ₇ C ₃ is obtained.

Further, in the above step 1), the rare earth yttrium block is a commercial rare earth yttrium block with a purity ≥ 99.5%.

Further, in the above step 2), the degree of vacuum is <10 ^-1 Pa.

Further, in the above step 2), the purity of the yttrium powder used is greater than 99.5%.

Further, in the above step 2), the purity and particle size of the Cr powder used are respectively: 99.9% and less than 100 μm.

Further, in the above step 2), the purity and particle size of the graphite powder used are respectively: 99.99% and less than 100 μm.

Further, in the above step 3), the degree of vacuum is <10 ^-1 Pa.

The present invention has the following beneficial effects:

The method for improving the anti-abrasion performance of Cr ₇ C ₃ blocks with rare earths of the present invention uses rare earth yttrium to improve the Cr ₇ C ₃ compound, adopts three kinds of powders of rare earth powder, Cr powder and graphite powder, and adopts two steps in the ball milling process. By controlling the appropriate ball milling process and sintering system, yttrium-doped Cr ₇ C3 carbides can be successfully prepared, and the toughness and oxidation resistance can be significantly improved. After the Cr ₇ C ₃ prepared by the present invention is doped with yttrium element, its toughness is increased by 0.6-1.5 times, and its wear resistance is increased by more than 1.8 times under high temperature oxidation atmosphere at 1000°C.

detailed description

The invention proposes a method for improving the anti-abrasion performance of block Cr ₇ C ₃ by rare earth yttrium. The appearance of the material can be applied to working conditions such as guide plates for hot-rolled steel. Concrete technical scheme of the present invention is:

Specific embodiments of the present invention are described below:

First, the commercial rare earth yttrium block material (purity ≥ 99.5%) is crushed to a particle size of less than 200 μm, and when the particle size is about 5-30 μm after ball milling under vacuum argon filling, the rare earth yttrium is sealed and stored under vacuum conditions.

Secondly, the commercially pure Cr powder and graphite powder are converted into weight ratios according to the atomic ratio in the molecular formula of carbide Cr ₇ C ₃ and the atomic weight of each element, and weighed separately. Vacuum (vacuum degree <10 ^-1 Pa), and ball mill for 10-20 hours.

Then, 2-3 hours after stopping the ball mill, the ball-milled yttrium powder (the amount added is 0.05-1.0% of the total weight of Cr powder and graphite powder) is added to the ball mill tank with Cr powder and graphite powder that have been mixed uniformly During the process, vacuumize again (vacuum degree is <10 ^-1 Pa) and turn on the ball mill, and ball mill for 30-50 hours. After the ball milling is completed, the uniformly mixed yttrium powder, Cr powder and graphite powder mixture are quickly filled into the mold .

Finally, put the graphite mold containing the mixture of yttrium powder, Cr powder and graphite powder into a sintering furnace for sintering. The sintering is carried out in a vacuum hot-pressing sintering furnace. The vacuum degree of the vacuum furnace during sintering is: ≤10 ^-1 Pa; the heating rate of the sintering furnace is: 5-10°C/s; the pressure is: 30-50MPa; the sintering temperature is: 1000°C-1400°C; .

Example 1

First, the commercial rare earth yttrium block material (purity ≥ 99.5%) is crushed to a particle size of less than 200 μm, and when the particle size is 20-30 μm after ball milling under vacuum argon filling, the rare earth yttrium is sealed and stored under vacuum conditions.

Secondly, the commercially pure Cr powder and graphite powder are converted into weight ratios according to the atomic ratio in the molecular formula of carbide Cr ₇ C ₃ and the atomic weight of each element and weighed respectively, and then the Cr powder and graphite powder are first put into a ball mill jar, Vacuumize (vacuum degree is 10 ^-2 Pa), and ball mill for 10 hours.

Then, 3 hours after stopping the ball mill, the yttrium powder (its addition is 0.05% of the total weight of Cr powder and graphite powder) after ball milling was added in the ball mill jar that the Cr powder and graphite powder that had been mixed uniformly were housed, and carried out again Vacuumize (vacuum degree is 10 ⁻² Pa) and turn on the ball mill, and ball mill for 30 hours. After the ball milling is completed, the homogeneously mixed mixture of yttrium powder, Cr powder and graphite powder is quickly filled into the mold.

Finally, put the graphite mold containing the mixture of yttrium powder, Cr powder and graphite powder into a sintering furnace for sintering. The sintering is carried out in a vacuum hot-pressing sintering furnace, and the vacuum degree of the vacuum furnace during sintering is 10 ^-2 Pa for sintering. The heating rate of the furnace is: 5°C/s; the pressure: 30MPa; the sintering temperature: 1400°C; the holding time: 120 minutes, and cool down together with the sintering furnace after sintering.

The toughness of the obtained bulk material (Cr, Y) ₇ C ₃ is about 0.6 times higher than that of Cr ₇ C ₃ , and the wear resistance is about 1.83 times higher at 1000°C under high temperature oxidation atmosphere.

Example 2

First, the commercial rare earth yttrium block material (purity ≥ 99.5%) is crushed to a particle size of less than 200 μm, and when the particle size is 5-15 μm by ball milling under vacuum argon filling, the machine is shut down and the rare earth yttrium is sealed and stored under vacuum conditions.

Secondly, the commercially pure Cr powder and graphite powder are converted into weight ratios according to the atomic ratio in the molecular formula of carbide Cr ₇ C ₃ and the atomic weight of each element and weighed respectively, and then the Cr powder and graphite powder are first put into a ball mill jar, Vacuumize (vacuum degree is 10 ^-2 Pa), and ball mill for 20 hours.

Then, 2.5 hours after stopping the ball mill, the yttrium powder (its addition is 1.0% of the total weight of Cr powder and graphite powder) after ball milling was added in the ball mill jar that the Cr powder and graphite powder that had been mixed homogeneously were housed, and carried out again Vacuumize (vacuum degree is 10 ⁻² Pa) and turn on the ball mill, and ball mill for 50 hours. After the ball milling is completed, the homogeneously mixed mixture of yttrium powder, Cr powder and graphite powder is quickly filled into the mold.

Finally, the graphite mold containing the mixture of yttrium powder, Cr powder and graphite powder is put into a sintering furnace for sintering. The sintering is carried out in a vacuum hot-pressing sintering furnace, and the vacuum degree of the vacuum furnace is ^10-1 Pa during sintering; The heating rate of the sintering furnace is: 10°C/s; the pressure is: 50Pa; the sintering temperature is: 1000°C; the holding time is: 60 minutes, and it is cooled with the sintering furnace after sintering.

The toughness of the obtained bulk material (Cr, Y) ₇ C ₃ is about 1.46 times higher than that of Cr ₇ C ₃ , and the wear resistance is about 2.3 times higher at 1000°C in a high temperature oxidation atmosphere.

Example 3

First, the commercial rare earth yttrium block material (purity ≥ 99.5%) is crushed to a particle size of less than 200 μm, and when the particle size is about 15-25 μm after ball milling under vacuum argon filling, the rare earth yttrium is sealed and stored under vacuum conditions.

Secondly, the commercially pure Cr powder and graphite powder are converted into weight ratios according to the atomic ratio in the molecular formula of carbide Cr ₇ C ₃ and the atomic weight of each element and weighed respectively, and then the Cr powder and graphite powder are first put into a ball mill jar, Vacuumize (vacuum degree is 10 ^-2 Pa), and ball mill for 15 hours.

Then, 2 hours after stopping the ball mill, the yttrium powder (its addition is 0.25% of the total weight of Cr powder and graphite powder) after ball milling was added in the ball mill jar that the Cr powder and graphite powder that had been mixed uniformly were housed, and carried out again Vacuumize (vacuum degree is 10 ⁻² Pa) and turn on the ball mill, and ball mill for 40 hours. After the ball milling is completed, the homogeneously mixed mixture of yttrium powder, Cr powder and graphite powder is quickly filled into the mold.

Finally, the graphite mold containing the mixture of yttrium powder, Cr powder and graphite powder is put into a sintering furnace for sintering. The sintering is carried out in a vacuum hot-pressing sintering furnace, and the vacuum degree of the vacuum furnace is ^10-1 Pa during sintering; The heating rate of the sintering furnace is: 7°C/s; the pressure is: 40MPa; the sintering temperature is: 1250°C; the holding time is: 90 minutes, and it is cooled with the sintering furnace after sintering.

The toughness of the obtained bulk material (Cr, Y) ₇ C ₃ is about 0.93 times higher than that of Cr ₇ C ₃ , and the wear resistance is about 1.9 times higher at 1000°C in a high-temperature oxidizing atmosphere.

Claims (2)

1. a rare earth improves block Cr ₇c ₃the method of anti-erosion performance, is characterized in that, comprises the following steps:

1) rare-earth yttrium block material is crushed to granularity below 200 μm, under vacuum argon filling condition, carry out ball-milling processing, when its particle diameter is 20-30 μm, shut down the airtight preservation under vacuum of rare-earth yttrium powder, described rare-earth yttrium block material is commercial rare-earth yttrium block material, purity >=99.5%;

2) Cr powder and Graphite Powder 99 are pressed carbide Cr ₇c ₃molecular formula Atom than and the nucleidic mass of each element is converted into weight ratio and after weighing respectively, first by Cr powder and Graphite Powder 99 loading ball grinder, vacuumize, vacuum tightness is < 10 ^-1pa, and ball milling 10-20 hour, Cr powder purity and granularity are respectively: 99.9% and be less than 100 μm; The purity of Graphite Powder 99 adopted and granularity are respectively: 99.99% and be less than 100 μm;

3) 2-3 hour after stopping ball mill, being added by rare-earth yttrium powder after ball milling is equipped with in the ball grinder of Cr powder and the Graphite Powder 99 mixed, the addition of rare-earth yttrium powder is the 0.05-1.0% of Cr powder and Graphite Powder 99 gross weight, again carry out vacuumizing and opening ball mill, vacuum tightness is < 10 ^-1pa, ball milling 30-50 hour, after the milling is completed, by the rare-earth yttrium powder, Cr powder and the Graphite Powder 99 mixture Fast Filling that mix in graphite jig;

4) by hold rare-earth yttrium powder, Cr powder, Graphite Powder 99 mixture graphite jig put into sintering oven and sinter, sintering carries out in vacuum sintering funace, and during sintering, the vacuum tightness of vacuum oven is :≤10 ^-1pa; The heat-up rate of sintering oven is: 5-10 DEG C/sec; Pressure is: 30-50MPa; Sintering temperature is: 1000 DEG C ~ 1400 DEG C; Soaking time is: 60 ~ 120 minutes, together cool after sintering with sintering oven, obtains the block Cr after rare earth improvement ₇c ₃.

2. rare earth according to claim 1 improves block Cr ₇c ₃the method of anti-erosion performance, is characterized in that, step 3) in, the yttrium powder purity of employing: be greater than 99.5%.