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自增韌氧化鋁陶瓷材料是通過在原料中加入可以生成第二相的原料,控制生成條件和反應(yīng)過程,直接通過高溫化學反應(yīng)或誘導氧化鋁晶粒的異向生長,使主晶相基體中生長出晶須均勻分布的、晶粒長徑比大的或晶片的增強體,形成陶瓷復合材料。這樣可以避免兩相不相容以及分布不均勻的缺陷,使強度和韌性都比用外來第二相增韌的同種材料高,從而進一步提高材料的力學性能。
裂紋在擴展過程中遇到長柱狀的顆粒時,沿結(jié)合較弱的顆粒/基體界面彎折,偏離與界面相垂直的方向,因而延長了裂紋在材料中的擴展路程,消耗更多的能量,從而達到增韌陶瓷材料的目的。
橋接增韌指當基體出現(xiàn)裂紋后,晶須像橋梁一樣承受外加載荷,并在基體的裂紋面之間架橋。橋聯(lián)機體斷裂面的晶須對機體產(chǎn)生使裂紋閉合的力,消耗外加載荷做功,從而增大材料的韌性和強度。
當基體裂紋擴展時,應(yīng)力集中導致結(jié)合較弱的晶粒與基體之間的界面解離;并在進一步應(yīng)變時導致晶粒在弱點處斷裂,隨后從基體中拔出。晶粒的拔出過程需要消耗一定的能量,從而達到增韌材料的目的。(圖/文tujian.net.cn)
中譯英:
During the crack propagation in cylindrical particles, along with weaker the particle / matrix interface of bending, perpendicular to the direction of deviation and interface, thereby prolonging the crack in the material expansion distance, consuming more energy, so as to achieve the purpose of toughening ceramic materials.
Bridging toughening refers to when the matrix crack, whiskers like a bridge under external load, and in the substrate between bridge crack. Bridge online body fracture surface whisker on the body to produce the crack closure force, consumption and load power, thereby increasing the toughness and strength of materials.