Coated cutting tool inserts
Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) coatings offer lots of benefits for numerous industries and applications.
For successful PVD or CVD coating, surface preparation is essential. Wet blasting is generally acknowledged as the best preparation technique for achieving the high levels of surface activation that are required for good coating adhesion. We cover the advantages of preparation for PVD and CVD coating by wet blasting below, but first, here are some of the advantages associated with these coating techniques.
Enhanced hardness and wear resistance: PVD and CVD coatings can significantly improve the hardness and wear resistance of the substrate materials. These coatings are typically composed of thin films of hard materials such as titanium nitride (TiN), titanium carbonitride (TiCN), diamond-like carbon (DLC), or various ceramic compounds. By applying these coatings, the surface hardness of the substrate can be increased, resulting in improved resistance to wear, abrasion, erosion, and scratching.
Improved lubricity and reduced friction: PVD and CVD coatings can exhibit low friction and excellent lubricity characteristics. These coatings can reduce the coefficient of friction between surfaces, minimising friction-related issues such as galling, adhesive wear, and frictional heat generation. This property is particularly beneficial in applications involving sliding or rotating components, leading to improved efficiency, reduced energy consumption, and extended component lifespan.
Increased corrosion resistance: PVD and CVD coatings can provide a protective barrier against corrosion. These coatings act as a physical barrier that shields the substrate material from exposure to corrosive agents, such as moisture, chemicals, or atmospheric elements. By preventing direct contact between the substrate and corrosive substances, PVD and CVD coatings help enhance the material's resistance to corrosion, oxidation, and chemical attack.
Temperature and thermal stability: PVD and CVD coatings can exhibit excellent temperature and thermal stability properties. These coatings are often used in high-temperature applications where the substrate material alone may not possess sufficient resistance. PVD and CVD coatings can withstand elevated temperatures, resist thermal shocks, and maintain their mechanical properties, making them suitable for applications such as cutting tools, turbine blades, engine components, and high-temperature environments.
Aesthetics and decorative appeal: PVD coatings, in particular, are known for their decorative properties. These coatings can provide a wide range of colours, including gold, rose gold, black, and various metallic finishes. PVD coatings are commonly used in the watch, jewellery, and automotive industries to enhance the appearance and visual appeal of products.
Reduced frictional heat and heat dissipation: PVD and CVD coatings can help manage heat generation and dissipation in applications where thermal management is critical. These coatings can improve the thermal conductivity of the substrate, enhancing heat transfer away from critical components. By reducing frictional heat, PVD and CVD coatings contribute to the overall temperature control, preventing overheating, and improving the efficiency and reliability of the system.
Customisation and versatility: PVD and CVD coating processes offer a wide range of coating options, allowing for customisation based on specific requirements. Different coating materials, thicknesses, and deposition techniques can be employed to tailor the coating properties to meet desired specifications. This versatility makes PVD and CVD coatings suitable for diverse applications across industries such as aerospace, automotive, medical, cutting tools, electronics, and more.
These benefits highlight the advantages of PVD and CVD coatings in terms of improving the performance, durability, functionality and even the look of various components and surfaces.
Watch with a gold PVD coating, burrs with blue and gold PVD coatings, and the PVD coating process itself
The benefits of preparing surfaces for PVD or CVD coating by wet blasting - Wet blasting, or vapor blasting, offers several benefits when it comes to PVD and CVD coatings:
Cleaning and surface preparation: Wet blasting effectively removes contaminants, oxides, and residues from the substrate's surface. This prepares the surface for coating by creating a clean, uniform, and textured surface, ensuring better adhesion of the PVD or CVD coatings.
Surface roughness control: Wet blasting allows for precise control over the surface roughness (Ra) of the substrate. By adjusting the abrasive media, water pressure, and blast parameters, the desired surface roughness can be achieved. In fact, wet blasting is more controllable than any other type of finishing process. This control is crucial for optimising the adhesion and performance of PVD and CVD coatings. As mentioned previously, wet blasting is generally acknowledged as the best preparation technique for achieving the high levels of surface activation that are required for good coating adhesion.
Reduced heat and damage: Compared to dry blasting methods, wet blasting generates less heat during the process. This lower heat reduces the risk of thermal damage to the substrate, particularly for heat-sensitive materials. The controlled cooling effect of the water helps maintain the substrate's integrity, allowing for the application of PVD or CVD coatings on delicate or temperature-sensitive components.
Enhanced coating adhesion: Wet blasting promotes superior coating adhesion by removing surface contaminants and providing an anchor pattern. The textured surface created by wet blasting increases the surface area available for the coating to bond, resulting in improved adhesion strength and durability.
Uniform coating thickness: Wet blasting helps ensure a more uniform coating thickness across the substrate. By removing surface irregularities and creating a controlled roughness, wet blasting eliminates variations in coating thickness, leading to consistent coating quality and performance.
Reduced porosity: Wet blasting can assist in reducing the porosity of PVD and CVD coatings. By cleaning the substrate thoroughly and enhancing the adhesion, wet blasting helps minimize the presence of voids and gaps within the coating. This improves the coating's density, corrosion resistance, and overall integrity.
Environmental benefits: Wet blasting is generally considered a more environmentally friendly process compared to dry blasting. The use of water as a carrier medium reduces airborne dust and the dispersion of hazardous materials, resulting in a cleaner and safer working environment.
With so many advantages, including being regarded as the best surface finishing process for surface activation in preparation for PVD or CVD coating, it is no surprise that so many leading manufacturers have installed Vapormatt machines for this specific purpose.
