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Liquid phase sintering is the process of adding an additive to the powder which will melt before the matrix phase. The process of liquid phase sintering has three stages: rearrangement – As the liquid melts capillary action will pull the liquid into pores and also cause grains to rearrange into a more favorable packing arrangement.
Hexoloy is a registered trademark for a pressureless sintered form of alpha silicon carbide. Hexoloy SA is made by sintering silicon carbide powder. This process bonds the powder together to create a self-bonded product which is extremely hard and lightweight. It has a high resistance to corrosion, erosion, high temperature and thermal shock.
Pressureless sintering is another method for processing and densifying UHTCs. Pressureless sintering involves heating powdered materials in a mold in order to promote atomic diffusion and create a solid material. Compacts are prepared by uniaxial die compaction, and then the compacts are fired at chosen temperatures in a controlled atmosphere.
There are numerous possible refinements of the sintering process. Some of the most common involve pressing the green body to give the densification a head start and reduce the sintering time needed. Sometimes organic binders such as polyvinyl alcohol are added to hold the green body together; these burn out during the firing (at 200–350 °C ...
Historically, liquid phase sintering was used to process ceramic materials like clay bricks, earthenware, and porcelain.Modern liquid phase sintering was first applied in the 1930s to materials like cemented carbides (e.g. WC-Co) for cutting tools, porous brass (Cu-Sn) for oil-less bearings, and tungsten-heavy alloys (W-Ni-Cu), but now finds applications ranging from superalloys to dental ...
Sintering of ZrB 2 is hindered by the material's covalent nature and presence of surface oxides which increase grain coarsening before densification during sintering. Pressureless sintering of ZrB 2 is possible with sintering additives such as boron carbide and carbon which react with the surface oxides to increase the driving force for ...
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Sintering of NbB 2 is hindered by the material's covalent nature and presence of surface oxides which increase grain coarsening before densification during sintering. Pressureless sintering of NbB 2 is possible with sintering additives such as boron carbide and carbon which react with the surface oxides to increase the driving force for ...