In the process of mechanical alloying (MA), the powder will be refined by the impact of metal ball and get nano-crystalline pre-alloyed powder. The preparation of nano composite powder (＜20nm) by MA can direct sinter tungsten copper material, which has high density and uniform tissue. However, it has low efficiency and will bring in impurities during the long-time ball milling.

Compared with MA, co-reduction is a kind of process that refining tungsten and copper oxide ball or salts through ball milling, or Using a mixed solution of salts obtained ultrafine or nano-crystalline tungsten-copper compound mixed powder, and then get ultrafine or nano-crystalline tungsten copper mixed powder by reductive hydrogen H₂. After pressing and sintering, tungsten copper material properties can be remarkably improved. Co-reduction can be suitable for different raw material and different process, will not bring in any impurity so that it has bright prospects.

More information about tungsten copper electrode powder direct sintering, click here:

http://news.chinatungsten.com/en/tungsten-information/79974-ti-10240

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In part 1 we know that micro drilling means a special drilling cycle and precise rotation of micro drills which is made to spade shape of diameter less than 50μm. Here we talk about the first important geometric characteristic of tungsten carbide spade-type micro drills.

There are several important geometric characteristics of tungsten carbide spade-type micro drills. First, the point of the micro drill is not a point at all. Even on conventional twist drills, the end is not truly pointed. Instead, the end of the micro drill consists of a cutting edge (called the chisel edge) made by two intersecting planes which also define the two primary cutting edges of the drill. The chisel edge removes material primarily by extrusion and cutting at high negative rake angle. The specific cutting energy along the chisel edge is relatively large compared to the drill's primary cutting edges. The chisel edge also adds to the drilling complexity because of the lack of a point. As the rotating micro drill first contacts the work piece (remember the micro drill has a very small structural rigidity) anything on the surface, including micro roughness and material slope, will cause the drill to walk on the surface as it is trying to begin removing material. Walking is characterized by an eccentric motion of the drill as it turns perhaps coupled with a non-time- varying bending of the drill about its longitudinal axis. Depending on the feed per revolution of the drill during hole start-up, the drill may begin drilling at a slant with the drill deflected like an end-loaded cantilever beam (which it is with superimposed column loading). If permitted to continue, the drill will quickly break. If the drill is strong enough to survive the large stress imposed in it due to micro drilling at a slant, the resulting hole will be slanted rather than normal to the work surface.

(To be continued. This article is divided into several parts and this is part 2, for part 1 please refer to http://news.chinatungsten.com/en/tungsten-information/79981-ti-10250)

Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
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Mechanical alloying powder is different from casting metal or alloy material, its atoms coupling tightly and come into being solid solution or compounds. In general, Milling in a limited time only make contact at those points, lines and surfaces at or approaching the atomic distance of each component, and end up with a very uniform distribution of each component of a mixture or compound.

The principle is that extruding, crushing, welding, re-extruding and forming composite grains in the beginning of milling. And composite grains will emerge new atom surface, layered structure refine under the mechanical force. In the process of mechanical alloying, layered structure forming is a symbol of the beginning of elements alloying, which shortens the diffusion path of solid state atoms and accelerates tungsten copper alloying process. In addition, the larger lattice dislocation density, which in turn provides a fast diffusion path for the alloying proceeds, the alloy further accelerates the process.

More information about tungsten copper electrode powder direct sintering, click here:

http://news.chinatungsten.com/en/tungsten-information/79974-ti-10240

Tungsten Copper Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-copper.com/
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:sales@chinatungsten.com
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Micro drilling is characterized not just by small drills but also a method for precise rotation of the micro drills and a special drilling cycle. In addition, the walls of a micro drilled hole are among the smoothest surfaces produced by conventional processes. This is largely due to the special drilling cycle called a peck cycle.

The smallest tungsten carbide micro drills are of the spade type. The drills do not have helical flutes as do conventional tungsten carbide drills and this makes chip removal from the hole more difficult. Drills with a diameter of 50 micrometers and larger can be made as twist drills. Drills smaller than this are exclusively of the spade type because of the difficulty in fabricating a twist drill of this size.

 (To be continued. This article is divided into several parts and this is part 1, for part 2 please refer to http://news.chinatungsten.com/en/tungsten-information/79982-ti-10251)

Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn