What Are The Toughening Methods For Alumina Ceramics?

The structure of alumina ceramic material is corundum type,with the characteristics of ionic bonds,making the sliding system far less than metal,which leads to its lack of certain toughness and plasticity.Therefore,the fracture toughness exhibited is low,which restricts the wide application of alumina porcelain.

Brief introduction of toughening method:

Precipitation:

The precipitation method refers to the precipitation of various forms of Al3+ionic aluminum hydroxide in the raw material liquid by introducing an appropriate amount of precipitant into the raw material.The process of preparing high-purity ultrafine alumina powder.

Improved Bayer method:

The Bayer method is a method commonly used in the industry to prepare alumina powder.In the process of preparing alumina by this method,the raw material sodium aluminate contains a large amount of impurities such as Si,Fe,K,Ti,etc.,so that the purity of the prepared alumina powder is somewhat reduced.Based on the traditional preparation process,the sodium aluminate and the crystallized alumina are subjected to dedoping treatment to prepare alumina powder with relatively high purity.This method is the modified Bayer method.

The raw material used in this method is mainly sodium aluminate,which has a wide range of sources and will not cause pollution during the entire process.However,due to its relatively complicated preparation process,alumina production efficiency is low,which limits its application in more fields.

Active high-purity aluminum hydrolysis method:

The active high-purity aluminum hydrolysis method is a method of using high-activity metal aluminum to react with water to generate aluminum hydroxide.The product is dried and calcined at high temperature to obtain high-purity alumina.The method is simple in operation and low in production cost,but the purity of the prepared alumina may be reduced.

Thermal decomposition of aluminum hydroxide:

Aluminum hydroxide thermal decomposition method is a method of preparing high-purity alumina powder by heating and decomposing high-purity aluminum hydroxide to a certain temperature.However,the complete conversion of aluminum hydroxide to α-Al2O3 usually requires a high temperature of about 1200 ℃,such a high calcination temperature will promote the rapid growth of alumina grains,forming hard agglomerated powder,affecting product performance.Therefore,the reduced α-Al2O3 phase transition temperature was once a research hot topic.