Preparation method of salt-mist-corrosion-resistant hard-surface coating material used for thermal spraying

A coating material and salt-spray-resistant technology, which is applied in the coating, metal material coating process, molten spraying, etc., can solve the problems of poor salt spray corrosion resistance, high powder sphericity, and unstable corrosion resistance. To achieve the effect of improving corrosion resistance

Active Publication Date: 2013-05-01
BGRIMM ADVANCED MATERIALS SCI & TECH +1
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Problems solved by technology

However, the corrosion resistance of WC-Co coating is poor, and the corrosion resistance of the coating can be improved by adding a certain amount of Cr. The main components of commercially available WC-CoCr are Co: 8~12%, Cr: 3.2~4.5% , WC margin
There are mainly the following preparation methods in the prior art of WC-CoCr for thermal spraying: 1. The Chinese patent "Production Method of Spherical Thermal Spraying Powder" (CN102350503A) discloses mixing tungsten carbide, cobalt and chromium carbide in a certain proportion, Use spray drying method to granulate, and then obtain spray powder by degumming, sintering, crushing and other processes. This method has simple process, high hardness, but poor corrosion resistance; 2. Chinese patent "Production method of tungsten carbide-based spherical thermal spray powder" "(CN1686644A) published content related to a preparation method of WC-CoCr, which uses Co and Cr as the binder phase, adopts ball milling pulping, spray drying granulation, hydrogen protection sintering and other processes to prepare WC-CoCr Spraying powder, the powder prepared by this method has high sphericity, but the corrosion resistance is unstable; 3. The Chinese patent "A Production Process for Tungsten Carbide Cobalt Chromium Metal Composite Powder" (CN101693974B) discloses a method for preparing tungsten carbide cobalt chromium metal The production method of the composite powder is to control the pH value by controlling the ammonia concentration and temperature of the ammonium tungstate solution, then add cobalt nitrate and chromium nitrate solutions, dry and calcinate the generated co-precipitated crystals, and then carbonize to obtain tungsten carbide cobalt-chromium metal composite powder
The hard phase particles obtained by this method are fine and evenly distributed, but the process control is difficult and the corrosion resistance is poor
The reasons for the poor corrosion resistance of cobalt-chromium tungsten carbide prepared by the above methods are different. The powder binder phase prepared by method 1 is metal cobalt, and its salt spray corrosion resistance is poor; method 2 is obtained by sintering Co powder and Cr powder. The CoCr binder phase is made, but it is difficult to avoid the local enrichment of Co during the preparation process, and its corrosion resistance is unstable; in method 3, the chromium oxide is carbonized into chromium carbide cermet during the carbonization process, and the binder phase is mainly Also metallic cobalt obtained by carbon reduction of cobalt oxide, which has insufficient corrosion resistance

Method used

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] CoCr alloy powder with a Cr content of 28% was obtained by gas atomization, and the particles with a maximum particle size of less than 30 μm were used as raw materials. The CoCr powder was mixed with WC, in which CoCr accounted for 13% of the total weight, and added after 4 hours of dry grinding 20% of the total weight of the mixed powder was deionized water and 6.5% of the total weight of the mixed powder was polyvinyl alcohol as a wet grinding medium, and the wet grinding was performed for 8 hours to obtain a slurry. Send the slurry into the centrifugal spray drying agent, the diameter of the atomizing disc is 150mm, the rotation speed is 18000rpm, and the outlet temperature is 120°C. The obtained granules are heated in a degumming furnace to 600°C for degumming, kept for more than 1 hour, then placed in a vacuum furnace for sintering to 1150°C and kept for more than 2.5 hours, then cooled to below 100°C with the furnace, then released from the furnace, crushed and sc...

Embodiment 2

[0019] CoCr alloy powder with a Cr content of 33% is used for gas atomization, and particles with a maximum particle size of less than 5 μm are used as raw materials. The CoCr powder is mixed with WC, of ​​which CoCr accounts for 16% of the total weight, and added after dry grinding for 4 hours. 40% of the total weight of the mixed powder was deionized water and 15% of the total weight of the mixed powder was polyvinyl alcohol as a wet grinding medium, and the wet grinding was carried out for 8 hours to obtain a slurry. Send the slurry into the centrifugal spray drying agent, the diameter of the atomizing disc is 200mm, the rotation speed is 11000rpm, and the outlet temperature is 100°C. The obtained particles are heated in a degumming furnace to 800°C for degumming, kept for more than 1 hour, then sintered in a vacuum furnace to 1250°C for more than 2 hours, and then cooled to below 100°C with the furnace, then released, crushed and screened to obtain Powder suitable for spra...

Embodiment 3

[0021] CoCr alloy powder with a Cr content of 30% by gas atomization is used, and particles with a maximum particle size of less than 5 μm are used as raw materials. The CoCr powder is mixed with WC, of ​​which CoCr accounts for 14.5% of the total weight, and added after dry grinding for 4 hours. 30% of the total weight of the mixed powder deionized water and 9% of the total weight of the mixed powder polyvinyl alcohol were used as wet grinding media for 8 hours of wet grinding to obtain a slurry. Send the slurry into the centrifugal spray drying agent, the diameter of the atomizing disc is 200mm, the rotation speed is 15000rpm, and the outlet temperature is 100°C. Put the obtained particles in a degumming and sintering integrated furnace, heat to 700°C for 1 hour for degumming, then raise the temperature to 1250°C for more than 2 hours, then cool down to below 100°C with the furnace, and then come out of the furnace, crush and sieve to obtain a powder suitable for spraying . ...

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Abstract

The invention provides a preparation method of a salt-mist-corrosion-resistant hard-surface coating material used for thermal spraying. As the preparation method takes prealloyed cobalt-chromium alloy powder having a small particle size and tungsten carbide as raw materials to prepare cobalt-chromium tungsten carbide composite powder, so that the corrosion resistance of the material is improved. With the method, the problems that chromium is not uniformly distributed or exists in a form of chromium carbide in the former composite powder binding phase, and the corrosion resistance is weak are solved; the prealloyed CoCr powder is taken as a binding phase; Cr is uniformly distributed; a complete oxidation film can be formed on the surface of the binding phase; and the corrosion resistance of the material is improved.

Description

technical field [0001] The invention relates to the technical field of thermal spraying, in particular to a method for preparing a salt spray corrosion-resistant hard surface coating material for thermal spraying. Background technique [0002] WC-Co has good wear resistance and is often used as a thermal spraying material for wear protection at medium and low temperatures (540°C). However, the corrosion resistance of WC-Co coating is poor, and the corrosion resistance of the coating can be improved by adding a certain amount of Cr. The main components of commercially available WC-CoCr are Co: 8~12%, Cr: 3.2~4.5% , WC margin. There are mainly the following preparation methods in the prior art of WC-CoCr for thermal spraying: 1. The Chinese patent "Production Method of Spherical Thermal Spraying Powder" (CN102350503A) discloses mixing tungsten carbide, cobalt and chromium carbide in a certain proportion, Use spray drying method to granulate, and then obtain spray powder by...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09D5/46B22F1/00B22F9/08C23C4/08C23C4/06
Inventor 任先京高峰马江虹李振铎田晔陆在平鲍君峰万伟伟
Owner BGRIMM ADVANCED MATERIALS SCI & TECH
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