Investigation on the key factors in the hydrothermal synthesis of BN： The way of introducing sodium azide

The way of introducing sodium azide (NaN_3) into the reaction solution played an important role in the preparation of cBN by hydrothermal synthesis method. The results showed that both cBN content and crystalline perfection of the samples improved with increasing R_N value, and pure cBN could be obtained at 300℃ and 10 MPa when R_N increased to 3:1. Here R_N is defined as R_N =NaN_3(I)/NaN_3(II), wherNaN_3(I) denotes the amount of NaN_3 (in molar) that is added into the autoclave at the beginning of threaction process, and NaN_3(II) is the amount of NaN_3 (also in molar) introduced into the autoclave ahigh temperature and high pressure (i.e. 300℃ and 10 MPa). In order to explain the experimental results, a preliminary model was proposed in this paper.

Investigation on the key factors in the hydrothermal synthesis of BN: The way of introducing sodium azide

The way of introducing sodium azide (NaN₃) into the reaction solution played an important role in the preparation of cBN by hydrothermal synthesis method. The results showed that both cBN content and crystalline perfection of the samples improved with increasing R _N value, and pure cBN could be obtained at 300°C and 10 MPa when R _N increased to 3:1. Here R _N is defined as R _N = NaN₃(I)/NaN₃(II), where NaN₃(I) denotes the amount of NaN₃ (in molar) that is added into the autoclave at the beginning of the reaction process, and NaN₃(II) is the amount of NaN₃ (also in molar) introduced into the autoclave at high temperature and high pressure (i.e. 300°C and 10 MPa). In order to explain the experimental results, a preliminary model was proposed in this paper. Supported by the National Natural Science Foundation of China (Grant Nos. 20473048 and 90206042), the Science & Technology Research Program of Ministry of Education (Grant Nos. 104110 and 305010), the Research Program of Ministry of Science and Technology (Grant No. 2005CCA00900), and Shandong Science and Technology Council (Grant Nos. 04BS04001 and 2005GG3203110)