Patents
The present invention provides a process for the manufacture of dense neodymium stabilized .beta.-Si3N4-.alpha.-SiAlON composite, wherein a synergistic composition essentially consisting of Si3N4, Al2O3, AlN, SiO2 and Nd2O3 as starting materials is mixed in proportion to make a total of 100 mole in the mixed batch, passing the powder through 100 mesh, pressing the powder to form green compacts, sintering the green compacts at a temperature in the range of 1700.degree. to 1900.degree. C. in nitrogen atmosphere. The process of the present invention provides neodymium stabilized .beta.-Si3N4-.alpha.-SiAlON composites by processing a composition from the system Si3N4--Al2O3AlN--Nd2O39AlN--SiO2 resulting into dense product of the order of >98% theoretical density with the advantages such as cost effectiveness, high hardness and high fracture toughness. The produced dense .beta.-Si3N4-.alpha.-SiAlON will be useful for low temperature applications such as wear parts like bearing and roller materials and particularly for grinding and milling operations like grinding balls.