The Mechanical Property And Microstucture Machinable Al₂O₃/CePO₄ Composite Ceramic

Based on the weak-bonding property between CePO₄ and Al₂O₃, machinable Al₂O₃/CePO₄ composite ceramics were designed and investigated, including reparation of CePO₄, choose of raw stuff powder and sintering of composite system by pressureless sintering process, analyzing the structure and properties of materials. We also valuation the machinable properties of materials.The experimental results indicated that the fracture toughness property was increased by adding the content of CePO₄, and obtain 3.6 MPa·m1/2 by adding 40% CePO₄ at the sintering temperature of 1600℃. Materials obtain high strength of 340MPa when the content of CePO₄ is 10%. And the strength began to decrease sharply by the increasing of CePO₄, but have a back-up when the content of CePO₄ achieve 40%.The study emphasized on the strengthening and toughening mechanics of materials. The layered tablets structure of CePO₄ making the deflection and bridging of crack path; On the other hand, the proper distribute of weak interface in the composite system format the network structure of weak and strong interfaces. It counteraction the fracture energy by format microcrack at the weak interface. This two mechanism assurance the reserve of strength when adding the weak component.Analysing the cause of decrease and increase of the strength by the increase of CePO₄ content. It mainly because when the CePO₄ content increasing, the increase of weak component make the falling of strength, but at the same time the mechanism of weak interface make a ascent trace of strength. Which is the main factor cause the change form of the strength.Machining tests have shown that the Al₂O₃/CePO₄ composite ceramics could be grinded and drilled using conventional metal-working stools. And the machining rationale for machinable ceramics was that, the bonding between CePO₄ and Al₂O₃ was weak and the bonding between Al₂O₃ and Al₂O₃ was strong, which distributed homogeneously and formed the network structure. Under the stress the superficial microcracks firstly formed along the weak bonding. With the stress increased, easy material removal occurred by deflection...