Abstract: A grinding method is provided in which abrasive is projected onto a steel product through a nozzle to perform grinding thereon such as in a continuous casting process or in a subsequent process, wherein high-pressure water jet mixed with the abrasive is projected onto the surface of the steel product to grind defects on the surface, etc. thereof. A grinding system for executing this grinding method is also provided, the system including supply sources of high-pressure liquid and abrasive, a nozzle device connected with these supply sources, an abrasive recovery device for recovering the used abrasive as needed and restoring the same to the supply sources, and combined detection systems.

Abstract: A high pressure injection nozzle member is formed of a super hard alloy or a hard material of carbide series mainly composing of a tungsten carbide as, wherein the tungsten carbon is composed of grains each having a diameter of less than 1 .mu.m. At least one kind of carbide or solid solution of carbide selected from Ti, Ta, V, Cr, Mo, Hf, or Zr by a weight % of less than 10.0% is added. A binding material essentially consisting of at least one of iron group elements by weight % of 0.2 to 2.0% may be further added. The super hard alloy or a hard sintered material has a high abrasion proof property and has a hardness more than about HRA 94.0. Nitride or nitride solid solution may be utilized in place of carbide or carbide solid solution. The nozzle member is particularly suitable for an abrasive water jet.

Abstract: A tube is formed from a polycrystalline silicon carbide having a density of from 3.18 to 3.21 g/cm.sup.3, a maximum impurity content of 20 ppm, and imperviousness to fluids by a process which comprises precipitating the silicon carbide on the surface of a rod-shaped graphite structure by a chemical vapor-phase synthesis method and thereafter removing the graphite structure. A water-jet nozzle of high resistance to abrasive wear can be produced by using this tube as an inner tube thereof to form the flow path for a water jet to be ejected therethrough.

Abstract: A high pressure injection nozzle member is formed of a super hard alloy or a hard material of carbide series mainly composing of a tungsten carbide as, wherein the tungsten carbon is composed of grains each having a diameter of less than 1 .mu.m. At least one kind of carbide or solid solution of carbide selected from Ti, Ta, V, Cr, Mo, Hf, or Zr by a weight % of less than 10.0% is added. A binding material essentially consisting of at least one of iron group elements by weight % of 0.2 to 2.0% may be further added. The super hard alloy or a hard sintered material has a high abrasion proof property and has a hardness more than about HRA 94.0. Nitride or nitride solid solution may be utilized in place of carbide or carbide solid solution. The nozzle member is particularly suitable for an abrasive water jet.