Toughening and Reinforcing Tungsten-Titanium Carbide-based Ceramics with Cubic Boron Nitride

Ceramic material is one of the most promising materials because of its excellent properties such as high temperature resistance, corrosion resistance and wear resistance. However, the brittleness of ceramic materials has been restricting its further development.

In order to meet the needs of the development of high-speed dry cutting technology and expand the variety and processing range of existing ceramic tools, some scholars have adopted a kind of tungsten titanium carbide ceramic tool material with high strength and toughness and added cubic boron nitride and its preparation method. It is realized through the following technical schemes:

1.Tungsten carbide and titanium carbide powders are proportionally weighed, and (Ti, W) C suspension is prepared by using an appropriate amount of absolute ethanol as the dispersing medium. The suspension is fully stirred with an agitator and dispersed by ultrasonic wave for 20 minutes.

2.The nano-cobalt powder (Co powder) is proportionally weighed, and the suspension of Co is prepared with appropriate amount of absolute ethanol as the dispersing medium. The suspension is fully stirred by agitator and dispersed by ultrasound for 20 minutes. The nano-cubic boron nitride (c-BN powder) is proportionally weighed and put into a 250 ml beaker, and 100 ml of absolute ethanol is added to prepare the mixed solution, first in the ultrasonic wave. The solution was suspended by ultrasonic dispersion for 10 minutes in wave cleaner. The temperature of water bath pot was set at 80 C. 50% surfactant sodium dodecyl sulfate with nano-cubic boron nitride quality was added into the mixed solution. It was stirred at high speed for 1 hour under the condition of constant temperature water bath and for 1 hour under the condition of constant temperature water bath.

3.The solution is repeatedly pumped and washed by a recycled water vacuum pump. The final substance is dried in a vacuum box, sifted, and the modified nano-BN is collected. The c-BN suspension is prepared with an appropriate amount of absolute ethanol as the dispersing medium. The obtained (Ti, W) C, Co and c-BN are fully stirred and dispersed by ultrasound for 20 minutes. The suspension was mixed to obtain a multi-phase suspension, which was dispersed by ultrasound for 20 minutes and mixed evenly.

4.Pour the mixture into the ball mill tank, take nitrogen as the protective atmosphere, absolute ethanol as the medium, cemented carbide ball as the grinding body, the weight ratio of the ball is 1:10, and the ball is milled for 48 hours. Then, the mixture is continuously dried in the electrothermal vacuum drying box at a set temperature of 110 C for 48 hours, and sifted in the nitrogen flow after complete drying, and then the powder is loaded into the tank. Graphite mould, vacuum hot pressing sintering. The process parameters of hot pressing are as follows: holding temperature 1350 C, hot pressing pressure 30 MPa, holding time 60 min and heating rate 10 ℃/min. The tungsten titanium carbide ceramic tool material with cubic boron nitride is prepared.

The addition of cubic boron nitride to tungsten-titanium carbide-based ceramic tool material will cause some interference on the crack tip due to the existence of cubic boron nitride particles, which will reduce the stress intensity near the crack tip. Meanwhile, cubic boron nitride particles will hinder the crack propagation and cause crack deflection and elimination. It consumes more fracture energy, so that the toughness of the material is improved. Compared with the existing ceramic tool materials, the ceramic tool materials have better mechanical properties while maintaining good friction and wear properties. It can be used to make ceramic tool and other wear-resistant and corrosion-resistant parts such as cutting tools.

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