The uniformity of metal nickel coated graphite coating prepared by wet pressurized hydrogen reduction method is better

Metallic nickel coated graphite materialIt is a type of composite particle material with a core-shell structure, which not only maintains the main characteristics of the metal coating and the coated particles, but also exhibits excellent comprehensive performance through composite effects resulting from the interaction of various components. Metal nickel coated graphite has applications in metallurgy, machinery, aerospace and many other fields Among them, Ni/C micro particles are a type of nickel coated powder material that has been applied earlier. They combine the corrosion resistance and toughness of metallic nickel with the solid lubricity and low thermal expansion coefficient of graphite, and occupy an important position in metallic nickel coated graphite materials. Until now, they still receive widespread attention and use At present, there are many methods for preparing Ni/C granular materials, such as chemical vapor deposition, sol gel method, chemical plating method, wet pressurized hydrogen reduction method, etc The wet pressurized hydrogen reduction method has simple equipment, economic feasibility, strong production scale and chemical composition controllability, and is currently the preparation method for industrial scale production of nickel coated graphite particle materials

The uniformity of nickel coated graphite coating is a very important research topic in the wet pressurized hydrogen reduction method for preparing N/C composite materials The "coating uniformity" referred to here is broad, including the distribution of the coating on the coated surface and the performance differences of the coating, such as the bonding strength between the coating and the coated surface, coating thickness, density (porosity), flatness, etc The uniformity of the coating has a significant impact on the performance of core-shell composite particle materials, which in turn affects the material's performance. Therefore, it is necessary to study the uniformity of NiC particle coatings

The factors affecting the uniformity of the coating during the wet pressurized hydrogen reduction method for preparing Ni/C from nickel coated graphite are complex and numerous There are many studies on the influence of dynamic factors such as reaction temperature, raw material ratio, additives, etc. on the uniformity of coatings,

The surface condition of core particles and the influence of coating times (B) on the coating have also been reported However, there have been no detailed and in-depth reports on the influence of particle size dispersion of core particles and H2 mass transfer process on the nickel plating effect on graphite surface The core particles themselves have a certain degree of particle size dispersion. Under a certain raw material ratio, different sizes of core particles participate in the coating process simultaneously, and the thickness of the coating will change. However, the regularity of the influence of this particle size dispersion of core particles on the thickness of the coating is currently unclear In addition, the influence of H2 mass transfer on the coating effect of coated granular materials is mainly focused on the study of stirring intensity and H2 partial pressure under a single stirring mode. However, there is little research on the differential effects of H2 mass transfer on coating uniformity under different stirring modes and intensities Therefore, in-depth research on the particle size dispersion of core particles and the influence of H2 mass transfer on the nickel coating effect on the surface of metal nickel coated graphite is of great significance for further understanding the coating process and mechanism of Ni/C composite materials

Nickel coated graphite composite powderIt is a composite powder material formed by coating a layer of metallic nickel on the surface of graphite core powder using chemical reduction method. Nickel coated graphite composite powder material not only has superior lubricating properties of graphite, but also has good electrical and thermal conductivity of metals. The preparation method of nickel coated graphite composite powder using chemical reduction has a uniform coating layer, good dispersion, and special physical and chemical properties, making it a new type of composite powder material.

Nickel coated graphite composite powder is prepared by chemical reduction method. When used as a thermal spray coating material, the metal nickel coated on the surface can prevent graphite oxidation caused by high temperature during the spraying process and improve the bonding strength between the composite material and the substrate; As a powder metallurgy material, it can increase the wettability between graphite lubricating components and the matrix, enabling graphite to be evenly distributed in the metal matrix phase and improving the overall performance of the material. According to the characteristics of the coating process and thermal spraying process, the nickel coating amount is generally divided into 60%, 75%, and 80%. Among them, 60% nickel coating amount is generally used for the preparation of sealing coating materials.

In terms of electromagnetic shielding and absorbing materials, nickel coated graphite composite powder is an important conductive filler. Nickel powder has good magnetic conductivity, but there are problems such as high density and high cost; The use of nickel coated graphite composite powder instead of nickel powder as a conductive filler not only has excellent conductivity and magnetic properties, but also has a low density and can significantly reduce material costs. Therefore, nickel coated graphite composite powder has broad application prospects as electromagnetic shielding, absorbing materials, etc.

With the development of thermal spraying technology, nickel coated graphite composite powder is still an important functional coating material. The spray coating prepared with this powder provides good bonding strength and required mechanical properties to the substrate during the running in and operation of sliding friction, while graphite acts as a solid lubricant, making the coating have good lubrication performance and wear resistance. Therefore, nickel coated graphite composite powder can also be used as a coating material for spraying wear-resistant sealing coatings on low-temperature components of engine compressors, self-lubricating coatings for non lubricated air compressors, self-lubricating coatings for organic solvent transfer pumps, etc.