A titanium aluminide (TiAl) coating capable of improving high-temperature oxidation resistance of titanium alloys and a preparation method thereof are provided. The TiAl coating includes α-AlF.sub.3 nanoparticles, and a content of the α-AlF.sub.3 nanoparticles is 5-30 vol. % of the TiAl coating. The preparation method of the TiAl coating includes: using a TiAl alloy target and an α-AlF.sub.3 target as raw materials, and performing magnetron sputtering on a substrate surface to prepare a coating; the magnetron sputtering is double-target co-sputtering, and a substrate temperature during the magnetron sputtering is 150° C., the TiAl alloy target is performed direct current sputtering with a power of 0.5-2 kW, and the α-AlF.sub.3 target is performed radio frequency sputtering with a power of 0.07-0.2 kW. After the coating is obtained by the double-target co-sputtering, the obtained coating is heat-treated at 600-800° C. for 5-20 h to obtain a final coating.

Mixed powder that contains first hard particles, second hard particles, graphite particles, and iron particles is used to manufacture a sintered alloy. The first hard particle is a Fe—Mo—Cr—Mn based alloy particle, the second hard particle is a Fe—Mo—Si based alloy particle. The mixed powder contains 5 to 50 mass % of the first hard particles, 1 to 8 mass % of the second hard particles, and 0.5 to 1.0 mass % of the graphite particles when total mass of the first hard particles, the second hard particles, the graphite particles, and the iron particles is set as 100 mass %.

A silver film for die attachment in the field of microelectronics, wherein the silver film is a multilayer structure comprising a reinforcing silver foil layer between two layers of sinterable particles. Each layer of sinterable particles comprises a mixture of sinterable silver particles and reinforcing particles. The reinforcing particles comprise glass and/or carbon and/or graphite particles. A method for die attachment using a silver film.

A pretreatment composition for metal that provides enhanced corrosion resistance, enhanced paint adhesion and reduced chip damage to a wide variety of metal substrates. The pretreatment is also cleaner because it is based on zirconium rather than zinc phosphates. The pretreatment coating composition in use preferably comprises 50 to 300 parts per million (ppm) zirconium, 0 to 100 ppm of SiO.sub.2, 150-2000 ppm of total fluorine and 10-100 ppm of free fluorine, 150 to 10000 ppm of zinc and 10 to 10000 ppm of an oxidizing agent and has a pH of 3.0 to 5.0, preferably about 4.0. The coating composition can optionally include 0 to 50 ppm of copper. The suitable oxidizing agents can be selected from a large group.

A silver film for die attachment in the field of microelectronics, wherein the silver film is a multilayer structure comprising a reinforcing silver foil layer between two layers of sinterable particles. Each layer of sinterable particles comprises a mixture of sinterable silver particles and reinforcing particles. The reinforcing particles comprise glass and/or carbon and/or graphite particles. A method for die attachment using a silver film.

Materials for die attachment such as silver sintering films may include reinforcing, modifying particles for enhanced performance. Methods for die attachment may involve the of such materials.

A method involves the coating of a metallic substrate with a blasting medium through sandblasting or equivalent techniques. The blasting medium is preferably a powder made of silicon nitride (or other ceramic or engineering materials). The sandblasting process allows the silicon nitride powder to form a loosely packed layer on the substrate. With additional treatment via rolling and/or sliding action against a secondary body in the presence of a liquid lubricant, the loosely packed particle layer turns into a flattened surface matrix consisting of particle clusters and irregular cavities. The silicon nitride particles are spontaneously attached to the substrate surface without the use of an adhesive agent which subsequently leads to the formation of a surface matrix exhibiting a chaotic hybrid topography with zero tensile stress when subjected to rolling/sliding contact pressure. This cluster-cavity matrix can evolve continuously (thus dynamic) and is immune to debris indentation from dirty lubricants. It is a complex, self organizing, and adaptive system. The practical value of this invention is to greatly enhance the fatigue and wear life of the bearing substrate and other objects coming into contact with the treated substrate.

A pretreatment composition for metal that provides enhanced corrosion resistance, enhanced paint adhesion and reduced chip damage to a wide variety of metal substrates. The pretreatment is also cleaner because it is based on zirconium rather than zinc phosphates. The pretreatment coating composition in use preferably comprises 50 to 300 parts per million (ppm) zirconium, 0 to 100 ppm of SiO.sub.2, 150-2000 ppm of total fluorine and 10-100 ppm of free fluorine, 150 to 10000 ppm of zinc and 10 to 10000 ppm of an oxidizing agent and has a pH of 3.0 to 5.0, preferably about 4.0. The coating composition can optionally include 0 to 50 ppm of copper. The suitable oxidizing agents can be selected from a large group.

A pretreatment composition for metal that provides enhanced corrosion resistance, enhanced paint adhesion and reduced chip damage to a wide variety of metal substrates. The pretreatment is also cleaner because it is based on zirconium rather than zinc phosphates. The pretreatment coating composition in use preferably comprises 50 to 300 parts per million (ppm) zirconium, 0 to 100 ppm of SiO.sub.2, 150-2000 ppm of total fluorine and 10-100 ppm of free fluorine, 150 to 10000 ppm of zinc and 10 to 10000 ppm of an oxidizing agent and has a pH of 3.0 to 5.0, preferably about 4.0. The coating composition can optionally include 0 to 50 ppm of copper. The suitable oxidizing agents can be selected from a large group.

Mixed powder that contains first hard particles, second hard particles, graphite particles, and iron particles is used to manufacture a sintered alloy. The first hard particle is a FeMoCrMn based alloy particle, the second hard particle is a FeMoSi based alloy particle. The mixed powder contains 5 to 50 mass % of the first hard particles, 1 to 8 mass % of the second hard particles, and 0.5 to 1.0 mass % of the graphite particles when total mass of the first hard particles, the second hard particles, the graphite particles, and the iron particles is set as 100 mass %.