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Features And Preparation Of Tungsten Carbide Mining Tool

June 22, 2018

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What is tungsten carbide blanks?

March 15, 2017

Tungsten carbide refers to the WC and Co powder as the main raw material, the use of powder metallurgy method by a series of processing technology mixing, pressing, sintering forming the alloy material. With hardness, high strength, corrosion resistance, stainless steel and other characteristics, widely used in hardware, machinery, chemicals, defense and other industries to produce high-precision high wear-resistant key components.

 

Performance characteristics

1, high density, g / cm2: 11.0 ~ 15.0 range, different uses of cemented tungsten carbide density is not consistent, it can be said that the different density of tungsten carbide use different, please note when buying.

2, high strength, different uses of hard alloy strength is not consistent, it can be said that different strength of tungsten carbide materials use different in the purchase is to pay special attention to this point.

3, high hardness, 82.0 ~ 93.6HRA, equivalent to 69 ~ 81HRC, different uses of hard alloy hardness requirements are not the same, it can be said that the different hardness of the use of different tungsten carbide, in the purchase is to pay special attention to this point

4, red hardness is good, up to 900 ~ 1000 ℃, 60HRC to maintain when no deformation.

5, good wear resistance, Machinable stainless steel, cast iron and other hard metal materials.

6, Magnetic property ,cobalt is a magnetic material, the magnetization law in line with the magnetic material of the magnetization curve. Therefore, tungsten carbide has magnetic properties. Magnetic properties can reflect the structure and composition of carbides and are therefore an important factor in the control of the production process.

7, Porosity, Porosity indicates that the microstructure of the carbide has micropores. The micropores of carbide products are very damaging to their strength, and the pores are the cause of carbide damage. The most effective way to eliminate and suppress carbide pores is to use sintered HIP or HIP (hot isostatic pressing) processes.

 

Types Of Tungsten Carbide

The Cemented Carbides are a range of composite materials, which consist of hard carbide particles bonded together by a metallic binder.

The proportion of carbide phase is generally between 70-97% of the total weight of the composite and its grain size averages between 0.4 and 10 μm.

Tungsten carbide (WC), the hard phase, together with cobalt (Co), the binder phase, forms the basic Cemented Carbide structure from which other types of Cemented Carbide have been developed. In addition to the straight tungsten carbide – cobalt compositions – Cemented Carbide may contain varying proportions of titanium carbide (TiC), tantalum carbide (TaC) and niobium carbide (NbC). These carbides are mutually soluble and can also dissolve a high proportion of tungsten carbide. Also, Cemented Carbides are produced which have the cobalt binder phase alloyed with, or completely replaced by, other metals such as iron (Fe), chromium (Cr), nickel (Ni), molybdenum (Mo), or alloys of these elements.

There are three individual phases which make up Cemented Carbide. In metallurgical terms, the tungsten carbide phase (WC) is referred to as the a-phase (alpha), the binder phase (i.e. Co, Ni etc.) as the b-phase (beta), and any other single or combination of carbide phases (TiC, Ta/NbC etc) as the g-phase (gamma). Other than for metal cutting applications, there is no internationally accepted classification of Cemented Carbides.

 

Typical product representative

1, tungsten carbide rods, commonly used to make drill bits, PCB board micro-drill, mold thimble, die top, electrode rods, gong knife, textile industry shuttle, machine journal, machine axis and so on.

2, tungsten carbide strip, commonly used to produce, woodworking tools, wear parts and so on.

3, tungsten carbide plate, commonly used to produce high-precision high wear-resistant mold, progressive die, anti-theft board, X-ray radiation board, cutting tools, shaped parts.

4, tungsten carbide wafer, commonly used to make round blade, such as: aluminum plate blade, cut the foot blade, tungsten carbide cutting blade, tungsten carbide V-CUT blade, V-CUT knife, tungsten carbide Cutting blade, tungsten carbide corrugated blade, fiber cutting blade and so on.

5, high temperature tungsten carbide materials, commonly used to produce ceramic sintering mold, tungsten carbide sintering mold.

 

Preparation

Carbide is made of tungsten carbide and cobalt in a certain proportion of mixing, pressed into a variety of shapes, and then semi-sintered.

The manufacturing process begins with the composition of a specific tungsten carbide powder mixture – tailored for the application.

The tungsten carbide powder is compacted into a form.

In a high-temperature sintering furnace, the tungsten carbide structure of the blank is shaped at precise temperatures for strictly defined periods. During this heat treatment, the tungsten carbide blank undergoes shrinkage of some 50% in volume.

The sintering process is usually carried out in a vacuum furnace. Placed in a vacuum furnace to complete the sintering, this time the temperature is about 1300 to 1500 degrees between.
Carbide sintering is to press the powder into a blank, and then into the sintering furnace heated to a certain temperature (sintering temperature), and maintain a certain time (holding time), and then cooled down, so as to obtain the required performance of cemented carbide materials.
Carbide sintering process can be divided into four basic stages:
1: removal of forming agent and pre-burning stage, at this stage sintered body changes as follows:
With the increase of temperature, the molding agent gradually decomposes or vaporizes to remove the sintered body. At the same time, the molding agent is more or less carbonized to the sintered body, and the carbon content increases with the molding agent The type, the number and the sintering process.
The surface oxide of the powder is reduced. At the sintering temperature, hydrogen can reduce the oxidation of cobalt and tungsten. If the molding agent and sintered in vacuum are removed, the carbon and oxygen reaction is not strong. The contact stress between the powder particles gradually eliminated, the bonding metal powder began to produce recovery and recrystallization, the surface diffusion began to occur, briquetting strength has improved.
2: solid phase sintering stage (800 ℃ - eutectic temperature)
In addition to the process of the previous stage, the solid-phase reaction and diffusion intensified, and the plastic flow was enhanced and the sintered body was significantly contracted at the temperature before the liquid phase appeared.
3: liquid sintering stage (eutectic temperature - sintering temperature)
When the sintered body appears liquid phase, the shrinkage is completed quickly, followed by a crystal transition to form the basic structure and structure of the alloy.
4: cooling stage (sintering temperature - room temperature)
At this stage, the alloy and the composition of the composition with the cooling conditions vary with some of the changes, you can use this feature, the carbide heat treatment to improve its physical and mechanical properties.

 

Instructions for use

1, tungsten carbide materials made of high-quality tungsten carbide, high hardness due to tungsten carbide and brittle, subject to external shocks easily broken, especially tungsten carbide cutting blade thickness is thin, by the external boxing More easily broken, so, in the installation of a variety of tungsten carbide materials used to prohibit beating, throwing tungsten carbide materials.

2, tungsten carbide edge of the material is extremely sharp, please pay special attention to the installation of safety, so as to avoid unnecessary personal injury.

3, tungsten carbide materials produced series of tungsten carbide products are particularly wear-resistant, its life is high-speed steel (white steel) several times, can greatly enhance your work efficiency and thus reduce your costs.

4, tungsten carbide materials because of a high hardness, so its processing is particularly difficult, feasible processing methods are as follows:

A, EDM (in the alignment, walking wire, fast wire processing)

B, welding processing: brazing, silver welding processing.

C, grinding: unintentional grinding, internal grinding, grinding plane, tool grinding processing, the use of grinding wheel is generally diamond wheel, depending on the process requirements.

D, laser processing: can be laser cutting forming, drilling, but the thickness of the laser by the laser power constraints.

 

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