Hot Coating Tungsten Carbide Molybdenum Carbide Mixed Powder

Ultrasonic spraying equipment for hot coating tungsten carbide molybdenum carbide mixed powder on the surface of ceramic products.

In the field of modern material surface engineering technology, ultrasonic spraying technology, as a high-precision and high-efficiency thin film preparation method, is increasingly demonstrating its unique advantages. Especially when processing high-performance ceramic components and coating their surfaces with superhard, high melting point metal ceramic mixed powders such as tungsten carbide and molybdenum carbide, this technology provides an almost ideal solution. The core goal of this process is to significantly improve the wear resistance, corrosion resistance, and high-temperature oxidation resistance of ceramic substrates under harsh working conditions by constructing a robust composite coating, thereby greatly expanding the application boundaries of ceramic materials and extending the service life of key components.

To achieve this goal, careful pretreatment of the ceramic substrate is essential. The surface of the ceramic product to be coated must achieve extremely high cleanliness and appropriate activity, and any trace of oil, moisture, or dust will become a weak link in the adhesion of the coating. Therefore, strict organic solvent ultrasonic cleaning, deionized water rinsing, and thorough drying are usually required. For ceramics with smooth and dense surfaces, it is sometimes necessary to introduce moderate sandblasting roughening or specific chemical activation treatment, aiming to increase the roughness and chemical activity of the substrate surface at the microscopic level, providing a stronger mechanical fitting and physical chemical bonding foundation for subsequent coatings.

Subsequently, it enters one of the most critical stages in the entire process – the preparation of spray coating slurry. This is not a simple physical mixing, but a precise process involving colloid chemistry and surface science. The particle size, morphology, and mixing ratio of tungsten carbide and molybdenum carbide powders directly determine the microstructure and performance orientation of the final coating. In order to uniformly and stably disperse these highly agglomerated fine powders in liquid media, it is necessary to carefully select a suitable solvent system (such as water-based or alcohol based organic solvents) and combine them with efficient dispersing agents. By continuous mechanical stirring and ultrasonic oscillation, the van der Waals forces between particles are disrupted to form a highly dispersed and settling stable suspension system. In addition, according to the process requirements, a small amount of temporary adhesive may be introduced to give sufficient initial strength to the unsintered “green” coating during the drying stage, preventing it from being damaged during transportation and furnace entry.

Next is the core stage of fully utilizing the advantages of ultrasonic spraying equipment – precision coating. Unlike traditional spraying methods that rely on high-pressure gas to break down liquids, ultrasonic spraying utilizes high-frequency mechanical vibrations generated by piezoelectric transducers to form fine capillary waves on the surface of the nozzle. When the amplitude exceeds the surface tension of the liquid, the slurry is broken into uniformly sized, mist like, and fine micrometer sized droplets. This unique atomization mechanism, coupled with a multi axis motion platform driven by a numerical control system, can achieve precise trajectory and uniform coverage scanning spraying on the surface of ceramic workpieces. By precisely adjusting parameters such as atomization frequency, feed rate, nozzle movement speed, and preheating temperature of the substrate, the thickness and shape of the wet film can be controlled extremely accurately, effectively avoiding common coating defects such as sagging, orange peel, or “coffee ring” effects, laying a solid foundation for obtaining high-quality coatings with consistent thickness and no macroscopic defects.

After spraying, the workpiece needs to undergo a gentle and controlled drying process. The purpose of this stage is to slowly and uniformly evaporate the solvent components in the slurry, avoiding cracking or curling caused by stress concentration inside the coating due to rapid drying. It is usually left at room temperature or sent to a low-temperature drying oven to ensure that the coating skeleton structure composed of powder particles, dispersants, and residual binders can be fully preserved.

Finally, the finishing touch that determines the final performance and bonding strength of the coating is high-temperature heat treatment, also known as the sintering process. This process is usually carried out under vacuum or high-purity inert gas protection to prevent the oxidation of active components at high temperatures. The sintering process needs to follow a carefully designed temperature curve: first, organic additives in the coating are removed at a slower heating rate (during the gel removal stage), and then quickly heated to a specific sintering window close to the melting point of the powder material but below the deformation temperature of the ceramic substrate for insulation. At this high temperature, tungsten carbide and molybdenum carbide powder particles undergo neck growth and densification through material diffusion. At the same time, mutual diffusion may also occur at the interface between the coating and the ceramic substrate, forming a strong metallurgical or chemical bond, ultimately obtaining a metal ceramic composite coating with dense structure, high bonding strength with the substrate, and excellent performance.

In summary, the use of ultrasonic spraying technology to prepare tungsten carbide molybdenum carbide mixed powder coatings on ceramic product surfaces is a systematic engineering technology that integrates advanced equipment, material science, and precision processes. It not only fully utilizes the huge advantages of ultrasonic spraying in uniformity, controllability, and high efficiency, but also successfully imparts the excellent performance of superhard materials to ceramic surfaces through subsequent optimized heat treatment processes, opening up a reliable and promising technological path for manufacturing new generation high-performance ceramic composite components that can work stably in extreme wear, corrosion, or high temperature environments.

About Cheersonic

Cheersonic is the leading developer and manufacturer of ultrasonic coating systems for applying precise, thin film coatings to protect, strengthen or smooth surfaces on parts and components for the microelectronics/electronics, alternative energy, medical and industrial markets, including specialized glass applications in construction and automotive.

Our coating solutions are environmentally-friendly, efficient and highly reliable, and enable dramatic reductions in overspray, savings in raw material, water and energy usage and provide improved process repeatability, transfer efficiency, high uniformity and reduced emissions.

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