Preparation of ZrB_2 Fine Powders Using Thermite Method by Reduction with Mg

The reactivity of starting materials and heat treatment conditions for the preparation of ZrB_2 fine powders using a thermite method were examined in the ZrO_2-B_2O_3-Mg and ZrO_2-B-Mg systems. The removal treatment of by-products was also investigated. In the ZrO_2-B_2O_3-Mg and ZrO_2-amorphous B-Mg systems, the reduction of ZrO_2 and B_2O_3 by Mg and the boriding reaction of α-Zr and Mg occurred concurrently. The ZrB_2 fine powders of single phase were successfully prepared at 1100℃ in the ZrO_2-B_2O_3-9Mg (molar ratio) system and at temperatures above 700℃ in the ZrO_2-2B-5Mg (molar ratio) system. Washing of the products with deoxidized acidic solutions in nitrogen atmosphere was effective to separate ZrB_2 from MgO and MgB_2, and to inhibit the oxidation of the ZrB_2, too. Mg content in the powders after the acid treatment was 0.6-1.0 wt%.rights: 社団法人日本セラミックス協会rights: 本文データは学協会の許諾に基づきCiNiiから複製したものであるrelation: IsVersionOf: http://ci.nii.ac.jp/naid/110002290151