Abstract: A sintered material based on silicon nitride for use in preparing cutting tools is provided. This material is prepared by sintering a mixture of silicon nitride containing 2-10 percent by weight of yttrium oxide, 1-5 percent by weight of aluminium oxide and 10-40 percent by weight of titanium carbide coated with titanium nitride under hot pressing or sintering followed by hot isostatic pressing at an elevated temperature ranging from 1600.degree. C. to 1800.degree. C. The coated titanium carbide in the form of powder can be formed by depositing a film of titanium nitride on the surface of titanium carbide in the presence of gaseous titanium tetrachloride, hydrogen and nitrogen under the partial pressure of 0.1 to 0.5 atmosphere at 1000.degree. C. to 1500.degree. C. The material can endow the cutting tools with higher toughness and strength and longer life.