Tungsten-Titanium-Tantalum-Cobalt Cemented Carbide Coated Preparation With Silicon Dioxide

The traditional preparation methods of sintered W-Co cemented carbides are usually composed of WC-TiC compound carbides and WC powder, Co powder through proportioning, ball milling, drying, mixing of forming agents, pressing and sintering. The toughness and flexural strength of the tungsten-cobalt-titanium cemented carbides prepared by this method have been improved, but the density and hardness of the materials are low, and the high temperature resistance is poor, so they can not be used as high-speed cutting tools. Tools can only be used for rough or semi-finish machining.

In view of the shortcomings of traditional technology, some scholars have proposed a preparation method of silicon dioxide coated tungsten titanium tantalum cobalt cemented carbide. The main processes are high temperature carbonization and chemical vapor deposition. Firstly, the oxides of WC, cobalt powder, titanium and tantalum are carbonized at high temperature, then the mixed materials after carbonization are ground to powder, and the powders are coated with silicon dioxide. The cemented carbide material was formed after the mixed powders were calcined at high temperature. The specific operation steps are as follows:

(1)Tungsten carbide, titanium dioxide, tantalum oxide and ultra-fine cobalt powder are weighed according to the content ratio and mixed evenly.

(2)The mixture is carbonized in a high-temperature carburizing furnace at 1800-2300 ℃ for 1-3 H.

(3) After carbonization, the mixture is cooled to room temperature and grinded to powder with an average particle size of 1-5um.

(3)Put the powder into the chemical vapor deposition reaction chamber, vacuum extraction, preheating to 600-800 ℃, using silica precursor as raw material, control the evaporation temperature of the raw material to 90-120 ℃, enter argon, the rotating rate of the reaction chamber is 30-60 r/min, the reaction time is 20-60 min, after the reaction is finished, it will be cooled to room temperature and taken out.

(4)Collect the coated powders, mix them evenly and put them into the mould for high-temperature scorching. The temperature is 1150-1600 ℃ and the time is 1-3h. When the powders are cooled to room temperature, the tungsten-titanium-tantalum-cobalt cemented carbide coated with silicon dioxide is obtained.

The coated tungsten-titanium-tantalum-cobalt cemented carbide material has higher density and hardness, strengths and toughness have been improved, and high temperature resistance is better. As a high-speed cutting tool, its cutting speed has been improved, and the service life of the tool has been effectively prolonged.

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