DEEP HOLE DRILLING INSERTS,LATHE MACHINE CUTTING TOOLS,CARBIDE INSERTS

The following standards contain provisions in this standard by reference in the provisions of this standard.

Reference standard of tungsten contacts in cut-out:

Chemical analysis of tungsten ------ GB / T 4324.1-4324.30 --- 1984

Metallic Vickers hardness test method------ GB / T 4340 --- 1984

Metallic Rockwell hardness test method------ GB / T 230 --- 1991

Cut-out in Magneto test method------ JB / T 9864.2 --- 1999

Tungsten rod in cut-out contacts technical conditions ------ JB / T 9860.2 --- 1999

Sintered bar, rod crystal grain size of tungsten, molybdenum and alloys test method ------ GB / T 4197 --- 1984

Batch inspection Sampling procedures and sample forms (for continuous batch of checks) ------ GB / T 2828 --- 1987

 

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Ammonium paratungstate is a very desirable form of tungsten for many industrial applications. Much effort has been expended by industry in order to arrive at economical methods of producin this product. Tungsten is derived primarily ll'QIl'l scheelite ore which is substantially calcium tungstate. This is normally treated by dissolution under pressure in a sodium carbonate solution. In this manner an aqueous solution of sodium tungstate is formed which may be used as a starting point for the preparation of ammonium paratungstate. it will be obvious that this sodium paratungstate solution contains not only tungsten values but also impurities such as sodium carbonate, sodium molybdate, silica, sodium fluoride, phosphorous, and molybdenum. Of these contaminants, molybdenum is one of the most difficult to control. At the present time a complex multi-step process is needed for producing ammonium paratungstate from such industrial solutions while substantially avoiding Carbide Insert Manufacturer serious contermination of the product. A large number of pH changes are required which entail th use of large quantities of various acids and alkali Even with this complex procedure, however, impurities are almost always present in the final product.

 

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Tungsten (W) is the main raw materials of tungsten points, that is to say, analysis of tungsten points’ surface film from its electrode potential is similar to the analysis of tungsten.
Each species owns the characteristic of standard electrode potential, which is a kind of equilibrium electrode potential.

The standard electrode potential at 25 ℃

Metal	Ion	Electrode potential (V)
W	W	-0.2
tungsten carbide inserts Ni	Ni2+	-0.23
Ag	Ag+	+0.799
Cu	Cu2+	+0.34
Pb	Pb2+	-0.126
Fe	Fe2+	-0.44

Standard electrode potential---put a matter in some kind of solution, which contains matter’s ions, the potential difference between the matter and the standard hydrogen electrode is the very standard electrode potential when ion concentration is 1g / L. The metal will be more active when negative value of standard electrode potential is bigger; but it will be less active when standard electrode positive value is larger.

What can be drawn from the table is that the potential difference between W and Cu is the biggest, which is 0.54V. The points’ material electrochemical corrosion is prone to appear in a high temperature, high humidity environment. Nevertheless the corrosion between W - Ni is slighter than W - Cu’s, W – Ag’s. Electrochemical corrosion is not prone to occur since the potential difference of W - Ni is only 0.03V, whose. Therefore, adding a right amount of Ni can improve oxidation resistance property of tungsten points, which will reduce the formation of its surface film.

 

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The four steps are applies an axial pressure to the powder, produces plasma for activation of the powder particles through pulse current discharge, with a direct current resistance of the sample is heated up to the required temperature and maintained for a certain time and the stress relief step. The most obvious difference between SPS and PAS is the third step, which SPS is heating by pulse current and it does not use DC as hot source during the whole sintering process.

Compared to common hot pressed sintering, conventional sintering and hot isostatic pressing (HIP), tungsten carbide nozzle plasma activated sintering technology has many advantages. First of all, it uses a DC to heat powder material and a graphite mold directly, and uses switching DC pulse voltage to generate high-temperature plasma among the powder particles or between voids. Therefore, the operation will be more convenient and more precise in carbide cutting inserts sintering energy controlling. And the inside of material has been heated uniformly, the heat transfer efficiency improved, the material densification improved.
















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First of all, we should be in the form of law to explicitly prohibit the uses of dirty bombs, any countries, any persons can’t use any reasons to use the dirty bombs. Secondly, the states must strengthen the supervision of the use of radioactive substances. In addition, we can use the tungsten alloy shielding containers to store the radioactive dirty bombs, which have been manufactured, or already exists. The reason for using tungsten alloy shielding containers to shield the dirty bombs is that the tungsten alloy has great highly density and good corrosion resistance, which can not only have the good radiation shielding capacity for the dirty bombs, but also have the long storage capacity, in order to avoid the problems of the dirty bombs leaking that caused by corrosion of the containers. Finally, if one area is attacked by the dirty bombs, the government should immediately Deep Hole Drilling Inserts command people to evacuate from the area, in order to ensure the safety first of all, then enclosing the area and taking the scientific management to treat the radiation problems.