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National Standard of Tungsten Powder

Tungsten Powder National Standard GB/T 3458—2006(Instead of GB/T 3458—1982)

1 Range
The standard stipulates the requirement, testing method, testing rules, mark, packing, transport, storage and PO or contract form of tungsten powder.
The standard is applied to the tungsten powder by hydrogen reduction of tungsten powder.

2 Normative References
The following terms being referred has become the terms of this standard. The standard noted with date which may be adjusted thereafter does not apply to this standard. However, both parties can discuss whether to adopt these modified standards or not. Referred documents without date can be applied to this standard if there is any modification.
GB/T 1480 Testing for metal powder grain size composition-Dry Sieving Method
GB/T 2596 Testing of specific surface area of tungsten powder, tungsten carbide powder(Nitrogen absorption)
GB/T 3249 Testing method for refractory metal and compounds powder: Fsss method
GB/T 4324 Chemical analyse method of tungsten
GB/T 5314 Sampling method of powder metallurgy method

3 Requirement
3.1 Product range
3.1.1 Tungsten powder can be divided into FW-1, FW-2, FWP-1 by difference in chemical components and application. FW-1 is used as raw material for tungsten carbide powder and other machined material, FW-2 is used as raw material for high density shielding product. FWP-1 can be used as ion spray material.
3.1.2 Tungsten powder can be divided into 14 grades according to its different grain size.
3.2 Chemical components
Table 1 stipulates the impurity content

Table 1

3.3 Average grain size range and oxygen content is complied to Table 2

3.4 Apparent density and grain size distribution of FW-1、FW-2 is determined by both supplier and demander.
3.5 Grain size of FWP-1 is between 0.075mm(-200 mesh)~0.045mm(+325 mesh), the powder quantity is no less than 80%，apparent density is（4.0~8.0）g/cm3。
3.6 Appearance
3.6.1 Appearance of FW-1、FW-2 is light grey or dark grey. FWP-1 is light grey, the color of tungsten powder should be uniform.
3.6.2 There is no visual inclusions in product

4 Testing Method
4.1 Chemical analysis of tungsten powder should follow GB/T 4324.
4.2 Average FSSS size of tungsten powder follows GB/T 3249.
4.3 Specific surface area follows GB/T 2596.
4.4 Apparent density and grain size distribution of FW-1、FW-2 is determined by both supplier and demander.
4.5 Grain size testing of FWP-1 follows GB/T 1480, if the buyer has special requirement, it should be negotiated by both party.
4.6 Appearance of tungsten powder is checked by visual.

5 Testing rules
5.1 Inspection and acceptance
5.1.1 Product is tested by quality assurance department of supplier to insure the product is complied to the standard, the product quality certificate needed to be completed.
5.1.2 Demander can inspect the product according to this standard, if the testing result is differ from the standard, then supplier should bring it up within one month to the seller and negotiated by both party.If arbitration is needed, sampling should be taken by both party.
5.2 Lot grouping
Product should be examined by batch. Every lot is composited by the tungsten carbide powder of same grade, quantity is negotiated by both party.
5.3 Sample
Sample test follows GB/T 5314.
5.4 Testing result judgement
5.4.1 If there is one item of the product is disqualification, then double amount of sample needs to be tested. If it is still disqualification, then this batch is unqualified.
5.4.2 If one of the grain size, specific surface area, total carbon, free carbon, chemical carbon and oxygen content of the product is unqualified, then double amount of sample needs to be tested. If it is still disqualification, then this batch is unqualified.
5.4.3 Appearance of product is checked by barrel, unqualified barrrel can be scrapped.
5.4.4 When sieving of FWP-1 is unqualified, then double amount of sample needs to be tested. If it is still disqualification, then this batch is unqualified.

6 Mark, packing, transport and storage.
6.1 Packing of product adopt iron drums with double inner sealed polyethylene plastic bag, weight of each bag is determines by both parties.
6.2 Outter packing of product should mark: supplier's name, product name, grade, specification, log number, net weight, also marks of DAMP PROOF, UPSIDE and so on.
6.3 Quality certificate should be included in every batch of product. It should includes:
a) Supplier name, address, postcode;
b) Product name, grade;
c) Batch number;
d) Weight (net weight and gross weight);
e) Standard number；
f) Test result and seal of quality inspection department;
g) Inspector ID;
h) Inspecting date.
6.4 During the transportation process, the product should be away from moisture, and avoid violent collision.
6.5 Product should be installed under dry, ventilated, no acid-based atmosphere to avoid oxidation. From the date of receiving, FW-1 and FW-2 should not be installed over six months, FWP-1 should not be installed over 12months.

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