The metal ceramic powder with a particle size of 15-45 .Math.m and suitable for thermal spraying is prepared through a combination of mechanical ball milling, spray granulation, and vacuum sintering. The metal ceramic powder is sprayed on a surface of a steel substrate adopting the high velocity oxygen fuel (HVOF) technology with oxygen-propane as fuel and taking oxygen as a combustion improver, propane as fuel, nitrogen as powder feeding carrier gas, and air as a cooling medium to prepare and form the NiCrBSi—ZrB2 composite coating. The present disclosure solves the problem that ZrB.sub.2 ceramic is difficult to compact during sintering and improves powder bonding strength and fluidity. The preparation method is simple, has advantages of high coating deposition efficiency and convenient equipment operation, and is cost-effective. The preparation method can improve thermal corrosion resistance and high-temperature wear resistance of a surface of boiler, and prolonging lifetime of the boiler.

The metal ceramic powder with a particle size of 15-45 .Math.m and suitable for thermal spraying is prepared through a combination of mechanical ball milling, spray granulation, and vacuum sintering. The metal ceramic powder is sprayed on a surface of a steel substrate adopting the high velocity oxygen fuel (HVOF) technology with oxygen-propane as fuel and taking oxygen as a combustion improver, propane as fuel, nitrogen as powder feeding carrier gas, and air as a cooling medium to prepare and form the NiCrBSi—ZrB2 composite coating. The present disclosure solves the problem that ZrB.sub.2 ceramic is difficult to compact during sintering and improves powder bonding strength and fluidity. The preparation method is simple, has advantages of high coating deposition efficiency and convenient equipment operation, and is cost-effective. The preparation method can improve thermal corrosion resistance and high-temperature wear resistance of a surface of boiler, and prolonging lifetime of the boiler.

A method for obtaining a lead-free or low lead content brass billet subjects a mixture of lead-free or low lead content brass chips and graphite powder to extrusion, either direct or inverted. The method obtains lead-free or low lead content brass billets.

A method for obtaining a lead-free or low lead content brass billet subjects a mixture of lead-free or low lead content brass chips and graphite powder to extrusion, either direct or inverted. The method obtains lead-free or low lead content brass billets.

Described herein are compositions, methods, and systems for printing metal three-dimensional objects. In an example, described is a composition for three-dimensional printing comprising: a metal powder build material, wherein the metal powder build material has an average particle size of from about 10 μm to about 250 μm; and a binder fluid comprising: an aqueous liquid vehicle, and latex polymer particles dispersed in the aqueous liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm.

Described herein are compositions, methods, and systems for printing metal three-dimensional objects. In an example, described is a composition for three-dimensional printing comprising: a metal powder build material, wherein the metal powder build material has an average particle size of from about 10 μm to about 250 μm; and a binder fluid comprising: an aqueous liquid vehicle, and latex polymer particles dispersed in the aqueous liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm.

In a method for producing a material sheet, in particular a metallic material sheet, a green body containing solid-state particles is sintered at a sintering temperature by heating the green body during sintering at least partly using microwave energy in accordance with a defined temperature profile having a heating phase and an essentially isothermal hold phase. A temperature of the green body is ascertained contactlessly with a sensor, and a supply of heat energy is controlled as a function of the temperature of the green body. During the heating phase an average microwave power is supplied and during the hold phase another average microwave power is supplied which is less than the one average microwave power.

A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s. The magnet includes a crystal grain having a main phase including a TbCu.sub.7 crystal phase, and a volume ratio of the TbCu.sub.7 crystal phase to the main phase is 95% or more.

A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s. The magnet includes a crystal grain having a main phase including a TbCu.sub.7 crystal phase, and a volume ratio of the TbCu.sub.7 crystal phase to the main phase is 95% or more.

A multi-material three-dimensional printing apparatus is provided. The provided apparatus includes two or more print stations. Each of the print stations includes a substrate, a transportation device, a dispersion device, a compaction device, a printing device, a fixing device, and a fluidized materials removal device. The apparatus also includes an assembly apparatus in communication with the two or more print stations via the transportation device. The apparatus also includes one or more transfer devices in communication with the assembly apparatus. The apparatus also includes a computing and controlling device configured to control the operations of the two or more print stations, the assembly apparatus and the one or more transfer devices.