reactin Sintering (RS) is an innovative technique to hard face steel substrates with ternary boride cermets.This process has dual role:in situ formation of hard phases through chemical reactions and sinterbonding onto steel substrates.Of more commercial interest,the process yields a coated product which does not neeed post machining prior to final use.The process is as follow:the steel is initially coated with a mixture of elemental metal and boride source powders available as tape cast sheet,by a simple lay up process.The laminate on heating to high temperatures undergoes chemical reactions leading to formation of in situ ternary borides band temperatures undergoes chemical reactions leading to formation of in situ ternary borides and liquid phase bonding at the interface.Unidirectional shrinkage in the thickness direction and matching coefficient of thermal expansion between steel and the boride ensures a defect free interface.The stages of bonding have been modeled by monitoring hte interface growth with time.Quenching experiments are used to isolate the events leading to bonding.The phase development of boride layer is monitored through X-ray diffraction studies.Nanoindentation has been employed on the wear resistant boride phase to measure its stiffness and hardness.
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