Ferro-Tungsten 

Ferro-tungsten is a master alloy for the production of tungsten-containing steels.  The raw materials for ferro-tungsten production are rich ore or ore concentrates of wolframite or scheelite.  Also artificial scheelite or soft scrap can be used.  The tungsten trioxide in these compounds can be reduced either carbothermically in electric arc furnaces or metallothermically by silicon and/or aluminum.  Also a mixed carbothermic-silicothermic production is in use.

Commercial ferro-tungsten contains between 75 and 85% W.  It has a steel grey appearance and a fine-grained structure consisting of FeW and Fe₂W.  It is supplied in 80–100 mm lumps.

Melting Base

Melting Base is another master alloy in tungsten steel production. It can have various compositions according to the tungsten scrap material in use. The tungsten content varies depending on type between 10 and 38% besides iron and sometimes 5.5% Mo and also 5 to 10% Co.

Different types of scrap materials are mixed to meet the required composition. Reductive melting is done in electric arc furnaces and the melt is finally granulated by casting on a rotating disc and quenching in water (size <10 mm).

 

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Using HIP technology after vacuum sintering, tungsten carbide buttons will be harder, tougher and have good wear resistance and anti-corrosion. However, it costs too much to popularize. With the rapid development of technology, low pressure hot isostatic pressing appeared in the 1980s, which was based on HIP and made some improvements, It has lower pressure than HIP and combines sintering with other processes. It not only reduces the cost, but also remarkably improving the properties of tungsten carbide nozzle. In addition, low pressure hot isostatic pressing is widely used in wolfram (W), molybdenum (Mo), titanium (Ti) and some other refractory metals.











Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
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Tungsten carbide nozzle microwave sintering technology is a new sintering process, which has high heating speed, high energy efficiency, high heating efficiency and low pollution and other characteristics. It takes advantage of the special band of microwave and the material a basic fine structure to coupling for creating the heat so that the loss of dielectric material is heated to the sintering temperature of the material as a whole achieved good density of the material.

In the late 1980s, microwave sintering technology has been introduced in the field of materials science, and gradually developed into a new type of powder metallurgy rapid sintering technology. Its basic principle is different from conventional thermal heating process, which to the heating element reaches a certain temperature by convection, conduction or radiation. For traditional sintering, the material accepts the heat from outside so that it needs a long time for sintering and the grains will be growing up.




















Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
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However, there are some problems of tungsten carbide nozzle hot pressed sintering still exist, such as the complicated producing equipments, the control is strict, the limit of material, large energy consumption and low efficiency. After vacuum sintering, optimizes tungsten carbide nozzle by hot isostatic pressing (HIP), which can exclude the pores and structural defects inside the cemented carbide and enhance densification of the material. Hot isostatic pressing (HIP) is a process with high temperature and pressure through, the heating temperature is usually 1000°C-2000°C, the working pressure reaches 200MPa, and uses high-pressure inert gas or nitrogen in a sealed container as the pressure transmission medium, which excerts a uniform pressure for the material under the high temperature and high pressure. In the late of 1960s, HIP technology has been widely used in tungsten carbide.














Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:  sales@chinatungsten.com
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