New technology for surface treatment of hottest ma

New technology of material surface treatment

1 Salt bath nitrocarburizing (tufftride QPQ) technology

tufftride Q process is to carry out nitrocarburizing in alkali hydrofluoric acid salt tank after simple pre cleaning and preheating to 350 ~ 450 ℃ in air. The treatment temperature is usually 580 ℃, which is generally maintained for 60 ~ 120min. Under special circumstances, the temperature can be reduced or increased. Cooling is carried out in an oxidation type cooling tank within the temperature range of 350 ~ 400 ℃, and then the workpiece is cleaned with sprayed hot water. In addition to the slow cooling speed, which is beneficial to the dimensional stability of parts, oxidation cooling also has other benefits: ① significantly improve the corrosion resistance; ② The product on the surface of the part in the alkali hydroxide bath produces an oxide film; ③ Get better sliding performance

after oxidation treatment, the parts can be polished (tufftide QP) or polished and then processed in the oxidation tank (tufftide QPQ). During the subsequent oxidation treatment, the roughness of the polished surface will not change

2. Ion precipitation diamond film technology

deposit a layer of diamond-like carbon film on the surface of the finished tool or deposit a layer of diamond film on other substrates, and then weld it on the tool surface. The principle of preparing diamond films is to prepare ionic carbon first, and then recrystallize it on the surface of the workpiece. Due to the existence of amorphous carbon and graphite, in fact, in most cases, diamond-like carbon films are obtained

3. Thermal spraying technology

thermal spraying is to use the heat source to heat, melt or soften the spraying material, atomize the molten droplets or push the molten particles into sprayed particle bundles by the power of the heat source itself or the external air flow, and the tensile strength of three test pieces shall not be lower than the specified tensile strength value of the steel bar of this grade; After the material cannot be added, the three test pieces shall be broken outside the weld and sprayed to the substrate surface at a constant speed to form a coating

during the spraying process or after the formation of the coating, the metal substrate and the coating are heated, so that the coating melts on the surface of the substrate, and diffuses or melts with the substrate to form a spray welding layer combined with the substrate metallurgy, which is called thermal spray melting

advantages of thermal spraying: various methods, extensive coating, unlimited workpiece and simple process

types of thermal spraying: flame spraying, arc spraying, plasma spraying

1) flame spraying:

① ordinary flame spraying: take oxygen fuel gas as the heat source, heat the spraying material to the molten or semi molten state, and spray it on the pretreated substrate surface with high-speed air flow to form a coating with required performance

② explosive spraying: the county sends a certain proportion of oxygen and acetylene gas into the spray gun, and then mixes the nitrogen and the rest of the spraying powder through another inlet. When a certain amount of mixed gas and powder is filled in the gun, there is an electric spark plug to ignite, so that oxygen and ethylene can be at your ease. Jinan Practical Machine Factory Jinan new era Gold Testing Instrument Co., Ltd. welcomes you to call and inquire about the explosion of acetylene mixing, which will generate heat and pressure waves. The sprayed powder is heated at the same time of obtaining acceleration, impacting on the surface of the workpiece to form a dense coating

③ supersonic flame spraying: a special flame gun is used to obtain high-temperature and high-speed flame flow to spray refractory materials such as tungsten carbide and obtain spraying layers with excellent performance

2) arc spraying technology

① ordinary arc spraying: Taking the arc as the heat source, atomizing the molten metal wire with high-speed air flow, and spraying it to the workpiece surface at high speed to form a coating. Its characteristics: excellent coating performance, high efficiency, energy saving and economic, safe to use

② supersonic arc spraying: it is a newly developed surface treatment technology based on the ordinary arc spraying technology by improving the arc gun and power supply. It not only has the main characteristics of ordinary arc spraying technology, but also because of the improvement of its spraying speed, it reaches and exceeds the speed of sound, so that the coating quality is significantly improved, the bonding strength is significantly improved, and the porosity is greatly reduced. In the field of wear-resistant and corrosion-resistant surface protection, surface treatment has obvious application prospects superior to ordinary arc spraying

3) plasma spraying

thermal spraying with plasma arc as heat source. Its features: no deformation of parts, many kinds of coatings, and stable process

4. Laser surface modification technology

1) laser transformation hardening: the surface layer of iron carbon alloy material is rapidly heated and austenitized by laser irradiation, while the matrix remains cool; After the light beam is removed, the austenite zone is quenched by the rapid cooling of the matrix to obtain martensite and achieve the purpose of surface hardening

2) laser melting hardening (laser grain refinement): using higher laser energy than phase transformation hardening, the metal surface can melt rapidly and cause a large temperature gradient between the molten metal and the base metal. After the laser is removed, the molten metal solidifies rapidly, the surface obtains a very fine or ultra-fine structure, the surface component segregation is reduced, and the surface defects and microcracks can be fused. Laser melting can form a deep hardened layer

5. Electroless plating technology

in the case of no electricity, it is a new technology to directly immerse the metal or non-metallic workpiece in the chemical deposition solution below 100 ℃, and deposit the amorphous alloy on the surface of the workpiece through catalytic oxidation-reduction

6. Functional gradient material (FGM) technology

material in short, phenolic foam has excellent properties. Its microstructure and properties change in a gradient with the position and state of the material. That is, two incompatible materials are integrated through gradient transition

its preparation methods are mainly: deposition method, spraying method, sintering method, self propagating high temperature synthesis method, infiltration method, etc