Tech Team · Kintek Solution

CVD (Chemical Vapor Deposition) diamonds are lab-grown diamonds that exhibit properties similar to natural diamonds, including extreme hardness and excellent optical properties. The shape of CVD diamond surfaces is influenced by the growth process, which results in a polycrystalline structure with crystallite tips that can take on tetrahedral or pyramidal shapes. These shapes are a direct result of the microcrystalline growth process, where carbon atoms deposit onto a substrate in a controlled environment, forming a dense, pure coating with uniform thickness. The surface roughness and grain structure of CVD diamond evolve with thickness, leading to a non-uniform composition. This unique structure makes CVD diamonds suitable for various industrial applications, particularly in cutting non-ferrous materials, where their hardness and durability provide significant advantages over other materials like PCD.

Key Points Explained:

1. Polycrystalline Structure:

   • CVD diamonds are grown in a polycrystalline form, meaning they consist of multiple small crystals rather than a single large crystal. This structure results in a surface that is not perfectly smooth but instead has crystallite tips with distinct shapes.
   • The crystallite tips often take on tetrahedral or pyramidal shapes, which are a result of the microcrystalline growth process. These shapes contribute to the sharp-edged roughness of the diamond surface, making it highly effective for grinding and cutting applications.

2. Growth Process and Surface Formation:

   • The CVD process involves placing a substrate in a chamber filled with carbon-rich plasma. Over time, carbon atoms deposit onto the substrate, forming a diamond layer.
   • As the diamond layer grows, the surface roughness and grain structure evolve. The initial stages of growth may produce a smoother surface, but as the layer thickens, the crystallite tips become more pronounced, leading to the characteristic tetrahedral or pyramidal shapes.

3. Surface Roughness and Grain Structure:

   • The surface of CVD diamond is not uniform; it exhibits roughness that changes with the thickness of the diamond layer. This roughness is a direct result of the polycrystalline nature of the diamond, where each crystal grows independently, leading to a non-uniform surface.
   • The grain structure of CVD diamond is also non-uniform, with variations in crystal size and orientation. This non-uniformity is due to the growth process, where different crystals grow at different rates and in different directions.

4. Industrial Applications:

   • The unique shape and structure of CVD diamond make it highly suitable for industrial applications, particularly in cutting and grinding tools. The sharp-edged roughness and hardness of the diamond surface allow it to cut through non-ferrous materials with ease.
   • CVD diamond tools have a significantly longer tool life compared to PCD (Polycrystalline Diamond) tools, often lasting 2-10 times longer. They also perform approximately 35% better than PCD tools, making them a preferred choice in many industrial settings.

5. Optical and Mechanical Properties:

   • CVD diamonds have excellent optical properties, including high transmittance from deep ultraviolet to microwave wavelengths. This makes them suitable for use in optical applications where high transparency is required.
   • The mechanical properties of CVD diamond, such as its extreme hardness (8,500 kgf/mm²), make it highly durable and resistant to wear. However, it is not suitable for cutting steel, as high temperatures can melt the diamond, leading to faster tool wear.

In summary, the shape of CVD diamond is characterized by its polycrystalline structure, with crystallite tips that often take on tetrahedral or pyramidal shapes. This unique structure, combined with its excellent mechanical and optical properties, makes CVD diamond highly valuable in various industrial applications.

Summary Table:

Aspect	Description
Structure	Polycrystalline with crystallite tips in tetrahedral or pyramidal shapes.
Growth Process	Carbon atoms deposit on a substrate, forming a dense, pure diamond layer.
Surface Roughness	Evolves with thickness, resulting in a non-uniform, sharp-edged surface.
Industrial Applications	Ideal for cutting non-ferrous materials; 2-10x longer tool life than PCD tools.
Mechanical Properties	Extreme hardness (8,500 kgf/mm²) but unsuitable for cutting steel.

Interested in leveraging CVD diamond for your industrial needs? Contact us today to learn more!