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Quench polish quench (QPQ) is a specialized type of nitrocarburizing case hardening that increases corrosion resistance. It is sometimes known by the brand name of Tufftride, Tenifer or Melonite. [1] Three steps are involved: nitrocarburize ("quench"), polish, and post-oxidize ("quench"). [2]
Case-hardening or carburization is the process of introducing carbon to the surface of a low-carbon iron, or more commonly a low-carbon steel object, in order to harden the surface. Iron which has a carbon content greater than ~0.02% is known as steel .
This also inversely affects the depth of the case; i.e., a high carbon steel will form a hard, but shallow case. [14] A similar process is the trademarked "Nu-Tride" process, also known incorrectly as the "Kolene" process (which is the company's name), includes a preheat and an intermediate quench cycle.
A few typical hardening agents include carbon monoxide gas (CO), sodium cyanide and barium carbonate, or hardwood charcoal. In gas carburizing, carbon is given off by propane or natural gas . In liquid carburizing, the carbon is derived from a molten salt composed mainly of sodium cyanide (NaCN) and barium chloride (BaCl 2 ).
In 1972–1973, Philippines was beset by rice production shortfalls resulting from the series of typhoons and floods and fertilizer shortages spawned by the oil crisis.The resulting fourfold drop in rice production prompted the government to directly intervene in the operations of the fertilizer industry through the issuance of Presidential Decree (P.D.)
Precipitation hardening (also called age hardening) is a process where a second phase that begins in solid solution with the matrix metal is precipitated out of solution with the metal as it is quenched, leaving particles of that phase distributed throughout to cause resistance to slip dislocations. This is achieved by first heating the metal ...
Case hardening is a weathering phenomenon of rock surface induration. It is observed commonly in: felsic alkaline rocks, such as nepheline syenite , phonolite and trachyte ; pyroclastic rocks , as pyroclastic flow deposit, fine air-fall deposits and vent-filling pyroclastic deposits; sedimentary rocks , as sandstone and mudstone .
Flame hardening is a very common surface hardening technique, which is often used to provide a very wear-resistant surface. A common use is for hardening the surface of gears, making the teeth more resistant to erosion. The gear will usually be quenched and tempered to a specific hardness first, making a majority of the gear tough, and then the ...