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一、前言 陶瓷材料具有耐高温、耐腐蚀、比模量大、化学稳定性好等优点,但作为结构零件,陶瓷材料的韧性往往不能满足使用要求。因此,提高陶瓷材料的韧性将是材料科学发展的一大方向。 理论研究表明,陶瓷断裂韧性可用下式表示:K_(IC)=(αE_(γi))~(1/2)。E是杨氏模量,γi是破坏能量。所以,通过改善孔隙、应力、晶粒等来提高陶瓷材料的破坏能量,可以达到韧化陶瓷的目的。50年代,人们曾在陶瓷中添加金属,利用金属塑变来吸收一部分外负载能量;70年代末,发现了ZrO_2马氏体相变可有效地提高陶瓷材料的断裂韧性;纤维或晶须增韧陶瓷材料的研究也在广泛深入地进行中。但金属陶瓷的脆性改善有限,相变韧化致使材料高温强度大幅度下降,纤维增韧陶瓷的制备工艺比较复杂。本文以Al_2O_3陶瓷为基,力图将上述陶瓷增韧的诸方法加以综合,探讨该类陶瓷基复合材料的复相韧化成分和机理,为进一步深入研究陶瓷基高性能复合材料作准备。 二、试验材料及方法
First, the preface Ceramic material has the advantages of high temperature resistance, corrosion resistance, large specific modulus, good chemical stability, but as structural parts, the toughness of ceramic materials often can not meet the requirements. Therefore, to improve the toughness of ceramic materials will be a major direction of material science. Theoretical studies have shown that the fracture toughness of ceramics can be expressed by the following formula: K_ (IC) = (αE_ (γi)) ~ (1/2). E is the Young’s modulus, γi is the destruction energy. Therefore, by improving the porosity, stress, grain, etc. to improve the destruction energy of ceramic materials, can achieve the purpose of toughening the ceramic. In the 1950s, people used to add metal to ceramics and used metal plastic deformation to absorb some of the external load energy. In the late 1970s, it was found that the martensitic transformation of ZrO_2 can effectively improve the fracture toughness of ceramic materials; the toughening of fibers or whiskers The research of ceramic materials is also carried out extensively and deeply. However, the improvement of the brittleness of the cermet is limited, and the phase transition and toughening cause the material to have a sharp decrease in the high temperature strength. The preparation process of the fiber toughened ceramics is relatively complicated. In this paper, Al 2 O 3 ceramics as a base, trying to be the above methods of ceramic toughening to be integrated to explore the phase-toughening of these ceramic matrix composites components and mechanism for further study of ceramic-based high-performance composite materials in preparation. Second, the test materials and methods