溶胶-凝胶法对Al_2O_3陶瓷表面改性的研究

STUDY ON SURFACE MODIFICATION OF Al_2O_3 CERAMICS BY SOL-GEL

研究了八种不同陶瓷试样的抗弯强度和韦布尔模数。结果表明 ,试样的抗弯强度按线切割、粗磨、精磨、抛光、热处理、氧化铝一次涂层、氧化铝二次涂层、Al2 O3-SiO2 混合涂层的次序依次提高。而韦布尔模数以Al2 O3-SiO2 混合涂层最高 ,其次是热处理试样。理论分析可知 ,热处理过程可使裂纹钝化甚至弥合 ,减少了裂纹半径C ,因此提高了抗弯强度。涂层方法可以提高试样的抗弯强度 ,但可能使晶界与晶粒产生裂纹而导致韦布尔模数下降。由Al2 O3-SiO2 混合涂层试样的横截面SEM形貌图可知 ,该方法可使溶胶颗粒渗入基体更深 ,可以很好地弥合试样表层裂纹。

Bending Strength and Weibull modulus of eight kinds of ceramics samples were studied.It is shown that bending strength rises in the order of linear cutting,rough grinding,finish grinding,polishing,thermal treatment,coating once with Al 2O 3 sol,coating twice with Al 2O 3 sol,coating with composite Al 2O 3-SiO 2 sol.Weibull modulus of composite coating sample is the highest,and the thermal treatment sample next.It is known that thermal treatment can blunt the cracks and even heal them.So the radius of the cracks is reduced and bending strength is raised.The coating method can raise bending strength while leading to decrease of Weibull modulus because of causing the cracks of crystalline grain and the crystalline interface.But the composite coating can make the sol grain permeate the substrate deep so that the sruface cracks can be healed obviously.