Carbide
What is carbide?
Carbide is a composite material manufactured via powder metallurgy, consisting of tungsten carbide particles bonded together with a cobalt-rich binder. This material offers an excellent combination of hardness and toughness, making it a popular tool material for a variety of machining operations.
Properties of Carbide
The properties of carbide make it a top choice for a wide range of cutting tools. Typical properties of carbide include:
- Hardness: Resistant to flank wear and resists deformation.
- Toughness: Can withstand harsh operating conditions without breaking.
- Resistance to chemical reactions: Does not react with machined materials.
- Chemical stability: Resistant to oxidation and diffusion.
- Resistance to sudden temperature changes: Maintains its shape and performance under varying temperatures.
Carbide Manufacturing Process
Carbide is manufactured using powder metallurgy methods as follows:
- Producing metallic tungsten powder from ore
- Manufacture of tungsten carbide: Producing tungsten carbide particles.
- Production of any alloy carbides
- Adding cobalt: To create various powder grades.
- Adding pressing lubricant
- Pressing
- Pre-sintering
- Shaping
- Final sintering
- Hot isostatic pressing
After sintering, the pieces may require post-processing, such as polishing or sandblasting.
Tungsten Carbide Grain Size in Carbide
Tungsten carbide grain size is one of the most important factors affecting the hardness and toughness of carbide. Carbide can range from coarse to semi-coarse tungsten carbide grain size, providing a superior combination of hot hardness and toughness. Fine or ultra-fine grain sizes, on the other hand, improve sharpness and durability in mechanical and heat treatment.
Carbide Binder Properties
The cobalt used as a binder in carbide significantly affects the material's toughness and resistance to plastic deformation. A higher binder content increases toughness but may reduce resistance to plastic deformation. Optimal properties are achieved by balancing the right cobalt content with the tungsten carbide grain size.
Gradient-sintered Carbides
The purpose of gradient sintering is to improve a material’s resistance to plastic deformation and edge toughness. This is achieved by concentrating cubic carbonitrides at the steel edge, enhancing hot hardness where it is needed most. This technique is especially suitable for many primary turning applications of steels and stainless steels.
Applications of Carbide
Coated carbide is the primary choice for a wide range of uses. Coated carbides, such as CVD and PVD coatings, provide improved wear resistance and toughness, making them suitable for nearly all types of machining. Typical applications include:
- Solid carbide drills and end mills
- Parting and grooving tools
- Milling and finishing grades
Uncoated grades of carbide are less common, but they are used especially for machining heat-resistant superalloys and titanium alloys as well as for turning hardened materials at low speeds.
Summary
Carbide is an extremely versatile and durable cutting tool material with a wide range of uses in the metalworking industry. Its combination of hardness, toughness, and chemical resistance makes it an ideal material for manufacturing various cutting tools. The manufacturing process for carbide is complex, but the resulting products offer superior properties that enhance the efficiency and quality of machining operations.
