Structure And Properties Of Ceramic Prepered By Dopping Al₂O₃ In ZrO₂

Introduction Ceramet composites are usually a kind of multiphase solid-composites,which are combined with two or more than two materials different in physicaland chemical properties. These composites are not only superior to anycomponent of its composites, but also are provided with unique properties thatits component doesn't have. Therefore, methods are in accordance withrequisitions of properties to be prepared, which have a great future and havebecome a hotspot in study. Al2O3 and ZrO2, as two classical ceramet materials, have been greatlyapplied. The excellences of high pure Al2O3 are stabile in chemical capability,good at biological consistent, of biological inertia, strong rigidity, good atwearability, and less than 1~2 scalar in the ratio of abrasion compared withother composites, which have been greatly applied as structure and syntheticmedicine materials. ZrO2 initially was applied to Nernst lamps as functionmaterials, and then applied as heating component of high temperature electriccooker (1800℃) under the oxidation atmosphere. The conductivity of ZrO2 isbecause of the selectivity of oxygenion. Then oxygen sensor made of ZrO2 isused to measure content and pressure of oxygen, which is greatly used inmetallurgy, chemical, electric power, and atomic energy industries, to inspectthe content of oxygen in melting metal. However, there are some flaws in thetwo kind materials. Al2O3 belongs to brickle material and low impact toughness;the melting point of ZrO2 is low, and but it need high temperature to prepareeven properties and structure. All of this limits their applicants. To improvetheir properties, adding other elements to make composites has been an effectmethod.The methods to prepare composites are classical solid-phase reaction andmechanical alloying. Many studies have indicated that the method is evidenteffect to composites, because different methods lead different microstructure inmaterials. High pressure can effectively reduce space between atoms, change 74吉林大学硕士毕业论文state of electrons, and affect the process of phase transition, it could throwgreatly energy on matters under high pressure and high temperature, which hasbeen an effective method to synthesize new matters. In this paper, we select Al2O3 and ZrO2, prepared by mechanical alloying,and synthesize ZrO2- Al2O3 composites. We study the connection betweenconditions of preparation and structure and properties by systemic experiments.Our intention is to make foundations for exploring more function and newproperties composites.Experiment In the present experiment, Al2O3 and ZrO2 are chosen as starting materials.ZrO2- Al2O3 composites were prepare by means of mechanical milling and highpressure and high temperature technologies. Their structures are examined byX-ray diffractory (XRD) and scanning electron microscopy (SEM).Measurements of physics properties are perform by Ramman spectroscopy(RS), rigidity meter and IMPEDANCE.Results and Discussion1. Structure and physical properties of composites prepared by doping Al2O3 in ZrO2 by means of high pressure and high temperature. Mixing ZrO2 and Al2O3 raw powder by different ratio (10%wt, 25%wt,40%wt Al2O3), preparing processed powder by means of mechanical alloying indifferent time (10h, 20h, 30h), then synthesizing composites by keeping powderunder 3.90Gpa and 1061℃. The results of XRD indicate that there are little 75吉林大学硕士毕业论文 metastable ZrO2 phases in different milling time. When Al2O3 is less than or equal to 0.25, C- ZrO2 appears; when Al2O3 is equal to 0.4,T- ZrO2 appears. However, there is no distinct rule between the appearance of metastable phase and milling time. Then high-pressure samples contenting metastable phase are dealt with high temperature by sintering 6 hours under 1000 , which don't make T- ZrO2...