PAN Deng 1, LI Shufeng 1, ZHANG Xin 1, PAN Bo 2, FU Yabo 3
(1. School of Materials Science and Engineering, Xian University of Technology, Xi’an 710048, Shaanxi, China;
2. Xi'an Thermal Power Research Institute Co., Ltd., Xi’an 710054, Shaanxi, China: 3. School of Physics and Electronic Engineering, Taizhou University, Taizhou 318000, Zhejiang, China)
Abstract: The key problems restricting the development of B4C ceramics are the high densification sintering temperature (>2200 °C) and the mismatch of fracture toughness and hardness. In this paper, the heat release via in-situ reaction of boron (B)-graphite (Gr)-WC system was used to reduce the densification sintering temperature, and the fracture toughness of the B4C matrix was reinforced by the trip-shaped W2B5 via in-situ reaction between WC-B. Graphite, boron and WC powders were ball milled by high energy planet ball milling and the powder mixture was consolidated by spark plasma sintering (SPS). The sintering parameters were shown as following: sintering pressure was set as 30 MPa, the three-step sintering temperature was 1100~ 1550~1700 °C and the duration time was set as 5~5~6 min. The influence of in-situ formed W2B5 content in the composites on microstructure and mechanical properties was studied. The strengthening and toughening mechanisms were also investigated. The experimental results showed when the B4C:W2B5=4:1 (mol), the composite ceramic shows positive effect on the mechanical properties which achieved an optimal counter-balance between fracture toughness and hardness, the relative density was 100%, the Vickers hardness reached 37.9 GPa, and the fracture toughness was 7.8 MPa·m1/2 when the sintering temperature was set at 1700 °C.
Key words: B4C-W2B5; spark plasma sintering; in-situ reaction; fracture toughness