Mechanical and tribological properties of calcia-magnesia-alumina-silica-based glass-ceramics prepared by in situ crystallization

摘要

CMAS glass-ceramics were prepared with natural minerals and industrial slag based on the glass system of CaO-MgO-Al_2O_3-SiO_2. Mechanical and tribological properties of the glass-ceramics were investigated. Results show that the bending strength and the Vickers hardness of the material increased with the increase of crystallization temperature. A glass-ceramics with 12.35 GPa of hardness and 366 MPa of bending strength was obtained by nucleated at 840 ℃ for 1 h and crystallized at 960 ℃ for 1 h. The main phases of the glass-ceramics are wollastonite (β-CaSiO_3) and diopside (CaMg(SiO_3)_2). Friction coefficient of the material is located in the range 0.05-0.6, which is very related to the contact pressure and sliding speed. Under a contact pressure of 0.1 MPa, the friction coefficient is less than 0.1, showing a good self-lubrication. The specific wear rate of the material is in a value of 10~(-3) to 10~(-6) mm~3 (N m)~(-1), depending on the test temperature and contact pressure. The wear rate is slowly increased from room temperature to 500 ℃, then obviously decreased from 500 to 800℃. It can reach to less than 10~(-5) mm~3 (Nm)~(-1) at 800 ℃ when the contact pressure is 0.1 MPa. Good wear resistance of the material is mainly depending on the ability to create plastic deformation and the critical yield stress to form microcracks.