Cemented Carbide Coating Technology: CVD & PVD

Cemented carbide coatings have transformed the landscape of manufacturing and machining, enhancing the performance and longevity of cutting tools, dies, and various industrial components. At the heart of these advancements are two prominent coating technologies: Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD). In this article, we'll delve into the fundamentals of CVD and PVD, explore their advantages.

• What Are CVD and PVD Technologies?

Chemical Vapor Deposition (CVD)

CVD is a process used to produce thin films and coatings by chemically reacting gaseous precursors to form solid materials on the substrate. In this method, a substrate (often made of metal or ceramic) is placed in a reactor, where it is exposed to a mixture of gases. These gases react chemically at elevated temperatures, resulting in a thin layer of material being deposited on the substrate's surface. 

The key steps involved in CVD are:

Gas Introduction: Precursors in gaseous form are introduced into a reaction chamber.
Chemical Reaction: The gases react at high temperatures, often around 800 to 1,000 degrees Celsius, leading to the deposition of solid material.
Coating Formation: As the reaction occurs, the material coats the substrate, forming a dense, adherent layer.

Physical Vapor Deposition (PVD):

PVD is a vacuum coating process that involves the physical transformation of material from a solid or liquid to a vapor and then back to a solid to form a thin film. This technology typically employs various methods to create a vapor, such as thermal evaporation or sputtering. 

The steps involved in PVD include:

Material Vaporization: The coating material (such as metal) is heated until it vaporizes.
Transport: The vapor moves through a vacuum environment to reach the substrate.
Condensation: The vapor condenses on the cooler substrate, forming a thin film.

• Advantages of CVD Technologies:

Compared with other coating methods, the CVD method not only has simple equipment and mature technology, but also has the following advantages:

1. There are many types of deposits, and metals, alloys, carbides, nitrides, borides, oxides, carbonitrides, oxynitrides, hydrogen carbonitrides, etc. can be coated.

2. It has high permeability and uniformity, and can obtain multi-layer coatings of different structures with uniform coating thickness.

3. The deposition rate is high and easy to control.

4. The coating has high purity, fine and dense grains.

5. Strong adhesion, thicker coatings can be obtained.

6. Low process cost, suitable for mass production.

• Advantages of PVD Technologies:

1. The coating temperature is lower than the tempering temperature of high-speed tool steel, so it will not damage the hardness and dimensional accuracy of high-speed tool steel tools, and no heat treatment is required after coating.

2. The effective thickness of the coating is only a few microns, so the original accuracy of the tool can be guaranteed, which is suitable for coating high-precision tools.

3. The coating has high purity and good density. The coating and the substrate are firmly bonded, and the coating performance is not affected by the substrate material.

4. The coating is uniform, and there is no thickening or rounding at the cutting edge and arc, so complex tools can also obtain uniform coating.

5. There will be no decarburization phase, and there will be no brittle cracking of the coating caused by chlorine erosion and hydrogen embrittlement deformation in the CVD method. The strength of the coated blade is relatively high.

6. The working process is clean, pollution-free and harmless.

• Milling coating options