This standard specifies the technical requirements, test methods, inspection rules, packaging and storage contents of silver tungsten carbide (12) graphite (3) electrical contact products. This standard applies to silver tungsten carbide (12) graphite (3) electrical contact products produced by powder metallurgy process for low-voltage switchgear. JB/T 7779-1995 Technical conditions for silver tungsten carbide (12) graphite (3) electrical contacts JB/T7779-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T 7779-1995
Technical Conditions for Silver Tungsten Carbide (12) Graphite (3) Electric Contacts Issued on October 9, 1995
Ministry of Machinery Industry of the People's Republic of China
Implementation on January 1, 1996
Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Silver Tungsten Carbide (12) Graphite (3) Electric Contacts 1 Subject Content and Scope of Application
JB/T7779-1995
This standard specifies the technical requirements, test methods, inspection rules, marking, packaging and storage of silver tungsten carbide (12) graphite (3) electric contacts.
This standard applies to silver tungsten carbide (12) graphite (3) electric contacts produced by powder metallurgy for low-voltage switchgear. 2 Reference standards
GB2828—87
GB5586—85
GB5587—85
JB/T7778—1995
3 Technical requirements
Batch inspection Count sampling procedures and sampling tables Basic performance test methods for electric contact materials
Basic shape, size, symbol and marking of silver-based electric contacts Chemical analysis methods for silver tungsten carbide electric contact materials 3.1 Electric contact products should meet the following physical and mechanical properties: Density||t t||Resistivity
Conductivity (IACS)
≥9.40(g/cm2)
≤3.40(μn.cm)
≥50.00(%)
Soft state ≥450(MPa）
Hard state ≥550(MPa）
Soft state ≥440(MPa）
Hard state ≥540(MPa）
One of the tests can be selected for the hardness value. The hard state means that the product has not been annealed and heat treated after the final re-pressing. 2 The nominal composition of the electric contact is silver 85wt%, tungsten carbide 12wt%, graphite 3wt%, and the product tolerance is: silver 85.0±1.0wt%, 3.2
total carbon 3.7±0.7wt%, free carbon 3.0±0.6wt%, total impurity ≤0.5wt% (added elements are not impurities), tungsten is the remainder. 3.3 Product dimensions and tolerances shall comply with GB5587 or the drawing requirements proposed by the user. 3.4 Product appearance quality The surface shall be free of cracks, stratification, and bubbles The surface roughness should meet the requirements of GB5587, and the height of the product burrs should be less than 0.15 num. 3.5 The metallographic structure of the product should be uniformly distributed with tungsten carbide and graphite particles, as shown in Figure A1 of Appendix A. The uneven structure is shown in Figure A2. The metallographic structure defect inspection of the product should observe the polished surface of the cross section of each sample. There should be no aggregates larger than 125u, inclusions or 55um pores, as shown in Figure A3 and Figure A4 of Appendix A. A4, Figure A5. 3.7 When the aggregates and inclusions in the metallographic structure are less than or equal to 125μm and greater than or equal to 75μm, and the pores are less than or equal to 55μm and greater than or equal to 35μm, no more than seven locations on the 4mm observation surface are allowed. If the cross section of the sample is large, it can be divided into several 4mm areas for observation, and then the total number of defects and total observation area are counted (the defect size and observation area are not the size after magnification). 3.8 When the length of aggregates and inclusions in the metallographic structure is greater than 35sa When m is less than 75um, the total area of ​​defects of aggregates and inclusions on the grinding disc surface exceeds 2.5% of the grinding disc surface area. When the pores are greater than 15μm and less than 35uμm, the pore area on the grinding disc surface shall not exceed 1.5% of the grinding disc surface area.
Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
3.9 If the product has a silver solder layer, the layer should be clearly marked. 4 Detection method
JB/T7779—1 995
4.1 The product size and burr shall be measured with a vernier caliper with a reading accuracy of 0.02mm and an outer diameter dry ruler with a graduation value of 0.01mm, or other suitable instruments and tools such as a projector. 4.2 The appearance quality of the product is generally visually inspected, and can also be observed with a magnifying glass or a tool microscope. The surface roughness of the product can be inspected as required by GB5587. 4.3
The physical and mechanical properties such as density, resistivity, Brinell hardness, Vickers hardness, etc. shall be measured in accordance with GB5586 and relevant The test method is as follows. 4.41
For contact products without ferromagnetic additives, the conductivity of the product can be directly measured by an eddy current conductivity meter. 4.5
For product component analysis, see JB/T7778.
4.7 For samples containing silver solder layer, the silver solder layer should be removed for chemical analysis and density and resistivity measurement. Metallographic defects of products are determined by using a metallographic microscope with a scale eyepiece to magnify 100 to 200 times and observe the polished and uncorroded fracture surface. 4.8
5 Inspection Inspection rules
5.1 The quality inspection of products is carried out batch by batch. Each batch of products should be of the same batch of ingredients and the same process. 5.2 The quality inspection of each batch of products shall be sampled according to the following requirements; 5.2.1 Appearance inspection 100% of each batch,
5.2.2 Dimension inspection shall be carried out according to the requirements of GB2828, with a secondary normal inspection sampling plan and a secondary general inspection level for sampling (see Appendix B Table B1). The arc radius and surface roughness of the electric contact shall be sampled and inspected according to GB5587. 5.2 .3 Density and hardness inspections are carried out according to the secondary normal sampling plan of GB2828, and the S-3 special inspection level is sampled (see Appendix B Table B1). 5.2.4 Chemical composition, resistivity and metallographic structure inspections are carried out according to the secondary normal sampling plan of GB2828, and the S-1 special inspection level is sampled (see Appendix B Table B1).
5.3 Chemical composition, density, hardness and metallographic structure inspections can be carried out on the same sample, and resistivity measurement is carried out on another sample prepared in the same process and the same material.
5.4 The qualified quality level of product hardness and density is 2.5, and the qualified quality level of size inspection is 4.0 except for thickness which is 2.5. The qualified quality level of chemical composition, resistivity and metallographic structure defects is 10. 5.5 In the first random inspection, if only one of the performance items does not meet the requirements, but meets the conditions for the second random inspection, only the unqualified performance can be re-inspected; if there are several performance items that do not meet the requirements in the first random inspection, but meet the conditions for the second re-inspection, these performance items should be tested at the same time. The qualified and unqualified judgment numbers of the first and second sampling are shown in Appendix B Table B1.5.6 The number of unqualified electrical contact products inspected is calculated based on the performance items.5.7 The user acceptance should be re-inspected according to the provisions of this standard within two months of receipt. If the re-inspection does not meet the technical requirements specified in this standard, the supplier should be notified within two months of receipt.
6 Marking, packaging and storage
6.1 Product marking shall be carried out in accordance with the requirements of GB5587.6.2 Each batch of products shall be accompanied by a product certificate and a quality guarantee, and stamped with the seal of the inspector and the technical quality inspection department6.3 The product certificate should indicate;
a) product name (or representative title), model or size specifications and batch number b) quantity (number or net weight);
inspection date;
d) manufacturer name
e) inspector name (or code) or inspection department (seal), 2
The content of the product quality assurance book should include:
JB/T7779—1995
product name (or representative title); model, size specifications and batch number; a)
product quantity (number or net weight);
product chemical composition, physical properties and metallographic structure photos; e)
inspection date:
manufacturer name;
inspector name (or code) or inspection department (seal): 6.5 Products should be packaged according to the same model and size specifications of the same batch. 6.6 If the unit weight of the product is less than or equal to 10g, it should be packaged in plastic bags. Each bag should not exceed 1kg. The plastic bags should not contain sulfur or chlorine corrosive gases, and moisture-proof measures should be taken. Vacuum packaging can be used if conditions permit. After packaging in plastic bags, they should be packed in paper boxes, one bag per box. If the unit weight of the contact is greater than 10g, 20-25 or one piece should be packaged in small plastic bags according to their weight and shape, and then packed in boxes. There should be measures to prevent the contact from rubbing and moisture. The weight of each box should not exceed 2kg. The name, specification, factory name, and trademark of the contact should be marked on the outside of the box, and the product certificate should be included in the box. Products packed in plastic bags or boxes should be shipped in packaging boxes and filled with soft materials. The weight of each box should not exceed 15kg. 6.7
There should be a packing list in the packing box, which should include: a)
Total number of bags (boxes);
Number of bags (boxes) of various types or sizes of electric contacts; Net weight or number of products;
Packing date
Seal of the packer;
Outside of the packing box should be marked:
Manufacturer name and address;
Consignee and address;
Gross weight and net weight;
Moisture-proof and shock-proof marks.
The product should avoid severe vibration during transportation to avoid mechanical damage. The product should be stored in a warehouse without corrosive media to prevent traceability JB/T7779-1995
Appendix
Metallurgical structure example
(reference)
A This example is a reference example of qualified and defective metallographic structures of silver tungsten carbide (32) graphite (3 electric contacts produced by powder metallurgy process. ≤》Distribution uniformly hooked qualified metallographic structure example (see Figure A1》8, silver powder finer matrix
b. Silver Coarse powder matrix
Figure A1 Tungsten carbide and graphite particles are evenly distributed in the silver matrix. Qualified metallographic structure photo (200X) Table 3 Metallographic structure with defects
43.3 Uneven distribution metallographic structure example (see A2) Figure A2 Metallographic structure photo of uneven distribution of tungsten carbide and graphite particles (200X) Maximum particle aggregation? 5m
3.2 Particle aggregation metallographic structure example (see A3) JB/T 77791995
Figure A3 Metallographic structure photo of particle aggregation (200-X) The longest dimension of particle aggregation is 125μm
A3.3 Metallographic structure illustration of inclusions (see Figure A4) Figure A Metallographic structure photo of inclusions (200X) The longest dimension of inclusions is 125um3
A3.4 Metallographic structure illustration of pores (now Figure A5) 5
JB/T7779-1995
Figure A5 Metallographic structure of pores Photo (200X) The longest dimension of pores is 55m
Gas-containing metallographic structure radiograph (200 years old
The longest dimension of gas ritual is 55m
JB/T7779-1995
Appendix B
Product inspection sampling table
(Supplement)
The data quoted in this appendix are partially extracted from GB2828 for reference when using this standard. B1
Second normal inspection sampling table (such as Table B1)). B2
Symbols in the table:!
Use the first sampling plan below the arrow. If the sample size is greater than or equal to the batch size, the entire batch will be inspected 100%; Use the first sampling plan above the arrow; Use the applicable sampling plan below;
Qualified number;
Re unqualified number,
Batch range
91~150
151~280
281~500||tt ||501~1200
12013200
3201~10000
10001~35000
35001150000
150001~500000
500000
Quantity code
Special inspection level
Inspection level
Sample plan table
JB/T 7779-1995
Additional remarks:
This standard is proposed and managed by Guilin Electric Science Research Institute of the Ministry of Machinery Industry. This standard is drafted by Guilin Electric Science Research Institute of the Ministry of Machinery Industry. The main drafter of this standard bzxz.net
Liang Bingjun
People's Republic of China
Mechanical Industry Standard
Silver Tungsten Carbide (12) Graphite (3) Electrical Contact Technical Conditions JB/T 77791995
Published by the China Academy of Mechanical Science
Printed by the China Academy of Mechanical Science
(No. 2, Shouti South Road, Beijing
Postal Code: 100044)
Number of words XXXXXX
Print sheets X/X
Format 880×1230
Edition X, XX, 19XX
Printing X, XX, 19XX
Number of prints 1-XXX
Price XXX.XX Yuan
XX-XXX
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