Abstract: A foam production method includes mixing liquid nitrogen with a foaming material to produce foam. A gas is produced in situ from liquid nitrogen. As the ratio of the volume of the gas produced by gasification of liquid nitrogen to the volume of the liquid nitrogen is relatively high, when a large gas supply flow is needed to generate a large foam flow, a liquid nitrogen storage device of a small volume can be used instead of bulky air supply devices such as high-pressure gas cylinders, air compressors, air compressor sets and the like, reducing the volume of the air supply device. In addition, the liquid nitrogen used in foaming will release nitrogen gas after the foam blast, such that the nitrogen is also able to inhibit combustion on the surface of burning materials, accelerating the extinguishing of the fire.

Abstract: A foam production method includes mixing liquid nitrogen with a foaming material to produce foam. A gas is produced in situ from liquid nitrogen. As the ratio of the volume of the gas produced by gasification of liquid nitrogen to the volume of the liquid nitrogen is relatively high, when a large gas supply flow is needed to generate a large foam flow, a liquid nitrogen storage device of a small volume can be used instead of bulky air supply devices such as high-pressure gas cylinders, air compressors, air compressor sets and the like, reducing the volume of the air supply device. In addition, the liquid nitrogen used in foaming will release nitrogen gas after the foam blast, such that the nitrogen is also able to inhibit combustion on the surface of burning materials, accelerating the extinguishing of the fire.

Abstract: A foam production method includes mixing liquid nitrogen with a foaming material to produce foam. A gas is produced in situ from liquid nitrogen. As the ratio of the volume of the gas produced by gasification of liquid nitrogen to the volume of the liquid nitrogen is relatively high, when a large gas supply flow is needed to generate a large foam flow, a liquid nitrogen storage device of a small volume can be used instead of bulky air supply devices such as high-pressure gas cylinders, air compressors, air compressor sets and the like, reducing the volume of the air supply device. In addition, the liquid nitrogen used in foaming will release nitrogen gas after the foam blast, such that the nitrogen is also able to inhibit combustion on the surface of burning materials, accelerating the extinguishing of the fire.

Abstract: The present invention is directed to a method for preparing a permanent magnet, and more specifically, to a method for preparing a high-performance sintered Nd—Fe—B permanent magnet, in order to solve the problems of increased brittleness or high cost present in the permanent magnet prepared by the existing process. A method for preparing a sintered Nd—Fe—B permanent magnet includes the step of ingredient calculation and raw material preparation including calculating ingredients and preparing raw materials according to the ingredient formula of the resultantly sintered Nd—Fe—B permanent magnet, and dividing the raw materials into a rare earth Fe—B compound and rare earth metals.

Abstract: The present invention is directed to a method for preparing a permanent magnet, and more specifically, to a method for preparing a high-performance sintered Nd—Fe—B permanent magnet, in order to solve the problems of increased brittleness or high cost present in the permanent magnet prepared by the existing process. A method for preparing a sintered Nd—Fe—B permanent magnet includes the following steps: (1) ingredient calculation and raw material preparation in which calculating ingredients and preparing raw materials according to the ingredient formula of the resultantly sintered Nd—Fe—B permanent magnet in mass fraction, i.e., (NdA?XREX)A(Febal?yMy)balB0.95˜1.03, in which A %+(0.95˜4.03)%+bal %=100%; then dividing the raw materials into a rare earth Fe—B compound and rare earth metals, the formula of the rare earth Fe—B compound in mass fraction being (Nd28?aREa)28(Febal?yMy)balB0.95˜1.03 and that of the rare earth metals being (NdA?28?bREb)A?28.