Study On In Situ Growth Nano-whisker Ceramic Tool

With higher heat resistance and abrasion resistance, modern ceramic cutting tool materials have shown unparalleled advantages in the field of high speed cutting than traditional tools. However, ceramic cutting tool materials have lower toughness and higher brittleness while whisker toughening ceramic cutting tool materials have higher toughness and can perform well under high temperature. Nowadays, plus a whisker is the main method on toughening ceramic cutting tool materials. But the cost of whisker preparation is high, besides, the process may do harm to both the environment and personal health. Therefore, the paper adopts in-situ synthesis of TiC whisker to toughen Al2O3 ceramic cutting tool materials, analyzes the growth mechanism of TiC whisker produced by the carbon thermal reduction method, studies the powder preparation process of the in-situ synthesis of TiC whisker, observes the sintering process, mechanical properties and micro structure of these materials.The paper analyzes the growth mechanism of whisker produced by the carbon thermal reduction method. The nature of whisker growth mechanism in the carbon thermal reduction method is SLLS. As is shown in the experiment that NaCl acts as the transport phase to send materials to Ni catalyst phase by adhesion and evaporation, which sustains the growth of TiC whiskers.This paper analyzes the preparation technology of in-situ synthesis TiC powder whisker toughening alumina ceramic cutting tool materials. As is clearly shown in the results that the most appropriate temperature in the carbon thermal reduction method is 1350℃. The content of free carbon would be reduced by second heating, thus, the mechanical properties of the cutting tool materials would be increased. Therefore, the best technology of growing whisker is that speed up the temperature to 1350℃ as quick as possible and sustaining the level for 80 minutes. Raise up the temperature to 1450℃ after grinding the materials, then stay for 30 minutes.This experiment optimizes the sintering technology range from 1600℃ to 1700℃, produces the TiC whisker toughening alumina ceramic cutting tool materials, and studies various influences of different sintering temperature and holding time on the material mechanics performance and micro structure. Results come that the best sintering technology are as follows: keep the sintering temperature of 1650℃ and sintering pressure of 35 MPa for 30 minutes, the bending strength of cutting tool material reaches 740 MPa, the fracture toughness of 6.8MPa?m1/2 and the hardness of 20.4GPa.The paper studies the toughening mechanism of TiC whisker on alumina ceramic materials, and comes up a new kind of toughing mechanism which functions within the nano-whisker.