Thermal Spray and Laser Cladding

       Laser cladding is one of the means to reduce the porosity of ceramic coatings (remelting the ceramic coating after thermal spraying with laser). Recently, a small partner asked, can laser cladding be used to directly prepare ceramic coatings. Why not? It's just that when choosing a surface treatment process, it is necessary to make a discretionary judgment according to the code of Price and Performance.



Laser cladding refers to using a high-energy-density laser beam as a heat source, presetting cladding layer powder on the surface of the substrate (for small area) or synchronous powder feeding (for large-sized workpieces), the laser beam Irradiation makes the powder completely melt and the base material slightly melts, so that the cladding layer and the base material achieve metallurgical bonding, thereby greatly improving the performance of the base material. A surface modification technology. Since light is used as the form of heating, it involves the absorption and reflection of light. In the laser cladding technology, the current utilization rate of light energy is at most 80%, which means that 20% of the light energy is absorbed by the powder. The material is reflected (why is this also a 28 rule?), fortunately, the cladding rate of this technology can be as high as 20-200m/min. Due to the small heat input, heat-sensitive materials, thin-walled and small-sized components can be used The technique performs surface cladding and can be used for entirely new material combinations, such as the preparation of coatings on aluminum-based materials, titanium-based materials or cast iron materials. If ultra-high-speed laser cladding equipment is used, the coating only needs to be simply ground or polished, so material waste and subsequent processing are greatly reduced. In terms of cost, efficiency, and thermal impact on parts, ultra-high-speed laser cladding can It has irreplaceable application advantages. So, let's not talk about the laser cladding of alloy powder (we will talk about it in a later issue), let's talk about the ceramic coating materials that our company has been producing for nearly 20 years: we recommend choosing HAP bioceramic materials, chromium oxide, high purity Alumina and other materials are matched with laser cladding technology (alumina-titanium composite materials can also be used, but the added value of the coating is decreasing year by year, and the profit is too low!). It is not recommended to use thermal barrier coating YSZ powder with this technology, because laser cladding makes the layered structure of the gradient coating disappear and the micro-cracks between layers reduce, resulting in thermal insulation and thermal shock resistance of the thermal barrier coating. decline.



In this article, we did not say which is stronger, thermal spraying or laser cladding, but only conveyed an idea by briefly introducing the characteristics of laser cladding technology: what is suitable is the best. For example, the recent news of the popular water sports Olympic trials: the first place in the preliminaries, but because the body side was ninth and did not make the top eight, Fu Yuanhui missed the finals... One-size-fits-all thinking is not good.