Effect of LZSA glass-ceramic addition on the erosive wear of pressureless sintered alumina

Abstract This study aims to evaluate the influence of the 11.6Li2O-16.8ZrO2-68.2SiO2-3.4Al2O3 (mol%) glass-ceramic addition (LZSA, 7 to 21 vol%) on the erosive wear of alumina in comparison to values of pure alumina obtained from the literature. Thus, composites were prepared from three commercial alumina of different initial particle sizes. Specimens were obtained by uniaxial pressing. Sintering temperatures and holding times were found to be different for each composite. The erosive wear test was carried out in an apparatus based on the standard ASTM G 76-4. The volumetric erosive wear (T vol) was correlated to the initial mean particle size of alumina, LZSA glass-ceramic content, average grain size of sintered alumina (AGS), porosity (P), elastic modulus, fracture toughness, natural defect size, and fracture energy based on a correlation matrix of statistical analyses. The experimental data of Tvol fit very well with P and AGS, individually, in a 3rd degree equation, except for composite AF21. Composite AF21, i.e. 21 vol% LZSA added to 0.5 µm mean particle size alumina (AF, fine alumina) and sintered at 1470 oC for 3 h, showed interesting results of T vol(2.05 × 10-8 m3·kg-1) related to the other investigated compositions, which varied from 1.90-4.37 × 10-8 m3·kg-1, and those existing in literature (0.55 × 10-8 to 10.78 × 10-8 m³·kg-1), mostly when considering the lower sintering temperature (1470 against 1600 oC). Thus, although the AC7 composite had shown the lowest Tvol value (1.90 × 10-8 at 1600 oC/7 h), the composite AF21 can be considered as the best result because of its lower sintering temperature and holding time (2.05 × 10-8 at 1470 oC/4 h). The formation of a viscous liquid phase, which crystallizes during the controlled cooling in the microstructure of the LZSA/alumina-based composites, improves the erosive wear of the alumina.

摘要 本研究旨在评估11.6Li₂O-16.8ZrO₂-68.2SiO₂-3.4Al₂O₃（摩尔百分比）系微晶玻璃（LZSA，体积占比7%~21%）的添加对氧化铝冲蚀磨损性能的影响，并与文献报道的纯氧化铝相关数据进行对比。研究采用三种不同初始粒径的商用氧化铝制备复合材料，通过单向压制成型得到试样，且不同复合材料所需的烧结温度与保温时长各不相同。冲蚀磨损试验基于ASTM G 76-4标准在专用装置上开展。通过统计分析构建的相关矩阵，将体积冲蚀磨损量（T_vol）与氧化铝初始平均粒径、LZSA微晶玻璃添加量、烧结后氧化铝平均晶粒尺寸（average grain size, AGS）、孔隙率（porosity, P）、弹性模量、断裂韧性、固有缺陷尺寸及断裂能进行关联。实验数据显示，除复合试样AF21外，T_vol分别与P、AGS均可通过三次方程实现良好拟合。复合试样AF21指向平均粒径0.5μm的氧化铝（AF，细氧化铝）中添加21%体积分数的LZSA，并在1470℃保温3h烧结得到的试样，其T_vol为2.05×10⁻⁸ m³·kg⁻¹，表现出优异的抗冲蚀磨损性能；本研究涉及的其余试样的T_vol介于1.90~4.37×10⁻⁸ m³·kg⁻¹，而文献中纯氧化铝试样的T_vol范围为0.55×10⁻⁸~10.78×10⁻⁸ m³·kg⁻¹，尤其当考虑更低的烧结温度（1470℃相较于1600℃）时优势更为突出。尽管AC7复合试样在1600℃保温7h烧结条件下获得了最低的T_vol值（1.90×10⁻⁸ m³·kg⁻¹），但AF21复合试样因采用了更低的烧结温度与保温时长（1470℃保温4h，T_vol为2.05×10⁻⁸ m³·kg⁻¹），可被视为本研究的最优结果。在LZSA/氧化铝基复合材料的微观结构中，可控冷却过程中结晶形成的粘性液相可有效改善氧化铝的抗冲蚀磨损性能。