Tungsten alloy electroplating technology development prospects good grasp plate rotation
Tungsten alloys are made of highly conductive copper and refractory tungsten.The metal tungsten and copper neither dissolve each other nor form intermetallic compounds, but only form false alloys. Therefore, w-cu alloy presents the comprehensive excellent properties of tungsten, such as high temperature resistance, high hardness, low expansion coefficient, high thermal conductivity, electrical conductivity, good plasticity and so on.Due to their high resistance to arc ablation, welding, impact and mechanical strength, they are widely used in environments with high corrosion and wear.
Tungsten alloy electroplating instead of chromium technology
Chromeplating is a traditional process, widely used in functional and decorative coatings. The annual output value of chromeplating industry in the United States reaches 8 billion dollars, and that in China exceeds 10 billion yuan.But the fatal shortcoming of this process is: the chromic acid concentration is high, the chromium-containing waste water and the waste gas pollution are big.The hexavalent chromium produced in chrome plating is a dangerous carcinogen.The environmental protection departments all over the world have carried out strict control on the discharge of chromium fog and chromium-containing wastewater.Therefore, the search for alternative chrome processes has become a requirement for all manufacturing.
Tungsten alloy electroplating process, there is innovation in coating composition, can obtain good toughness thick coating.The main characteristics of the technology is: (1) overcome the existing chromium plating process Cr6+ on the environment of serious pollution.(2) in the hardness, wear resistance and corrosion resistance of the main performance is equal to or better than chromium plating.(3) high material utilization, low production cost.(4) can make full use of the existing chromium plating process equipment, small transformation project.
The testing by the national authority and the use by the users indicate that the plating has good wear resistance, high hardness, improved service life, good machinability and abrasion resistance.The hardness of the coating is Hv = 600 ~ 1300Hv. The change of vickers hardness is directly related to the composition of the coating.Corrosion resistance: the corrosion resistance of the plates was measured by immersing the plates in 5% hydrochloric acid and 5% sodium hydroxide respectively.The coating remained intact after 72 hours immersion in 5% sodium hydroxide.Plating thickness: up to 0.3mm.
Coating and substrate adhesion: good coating and substrate adhesion can be obtained by proper pretreatment of different substrate materials.Base material shape: qualified coating can be obtained on various base materials.The popularization and application of this technology has good social and economic benefits.
Tungsten alloy electroplating overcomes the problem of sucker rod corrosion protection
Oil drilling equipment and production equipment encountered two major problems in the field application: corrosion and wear.In order to prolong the service life of sucker rod and tubing must improve abrasion of sucker rod and tubing corrosion protection performance of an enterprise according to the latest achievements in national 863 program - tungsten alloy electroplating technology, produce the permeability of tungsten alloy plating anticorrosive wear-resisting pipe rod (DSW), it is a kind of high and new technology products, has the following advantages: coating wear-resisting, corrosion resistant aspect has the very good comprehensive performance;Uniform coating;High material utilization, low energy and water consumption;No pollution, it's environmentally friendly.This product is the best solution to the two problems of wear and corrosion.
Abrasion resistance: excellent abrasion resistance under dry friction and lubrication.In the case of oil boundary lubrication, the friction coefficient is low, and the wear amount of friction pair is much smaller than that of hard chromium layer under the same dual condition.
Corrosion
resistance: with H2S, CO2, NaCl and other corrosive media, neutral salt fog test 300 hours can reach 10 grade, 5% sulfuric acid, hydrochloric acid and organic acid have no impact on it.
The coating is composed of A, B and C layers. Through process control, C layer is amorphous structure, B layer is layered crystallization, A layer is columnar crystallization, and the electrode potential of each layer is C > A > b. due to different crystallization, columnar pores and flake pores are not easy to coincide in one point, porosity decreases, and the probability of corrosion decreases.After the failure of the coating, in the corrosive environment, because the B layer has the lowest potential, as the anode, it causes transverse corrosion of the B layer. Protective corrosion occurs in the B layer first, and then the A layer is corroded, effectively protecting the matrix. Therefore, ABC structure has obvious corrosion resistance.
For relatively severe working conditions (salinity >100000mg/l), the closed structure of ABC+ polymer material can be adopted.The closed structure layer made of polymer material is added externally to reduce wear and reduce wear, which can effectively protect the oil well pipe and isolate the contact between the corrosive medium and the plating layer, and further increase the corrosion and wear resistance of the oil pipe and sucker rod on the basis of ABC structure.
Technical requirements for tungsten-plated antiseptic tubing and casing:
1. The chemical composition of the selected material conforms to the chemical composition requirements of SY/ t6194-7.1 in 2003. Metallographic test and tensile test will be carried out after the material enters the factory, and it can be used only after qualified.
2, the surface of the inner coating thickness 20 m, coating quality meet the requirements of thermal shock method.
3. Mechanical properties after plating shall meet the requirements of SY/ t6194-2003.
4. After plating, the surface quality shall meet the requirement of less than 3 pinholes per square meter.
5. The external dimensions after plating shall meet the requirements of SY/ t6194-2003 in 8.2.
6. The sealing surface and thread gauge rain after plating shall meet the requirements of 4.2.2 and 4.2.3 in GB/ t9253.2-1999.
7. Salt spray test does not change color for 96 hours.
8. The artificial seawater immersion method does not change for 60 hours.
Technical requirements for tungsten-plated antiseptic sucker rod and polished rod:
1. The material selection conforms to the material requirements of SY/ t5029-2003. After entering the factory, metallographic test and tensile test are carried out.
2, surface coating thickness 20 m, coating quality meet the requirements of thermal shock method.
3. Mechanical properties after plating shall meet the mechanical properties requirements in SY/ t5029-2003.
4. After plating, the surface quality shall meet the requirement of less than 3 pinholes per square meter.
5. The external dimensions after plating shall meet the requirements of SY/ t5029-2003 7.1.
6. The thread shall meet the requirements of SY/ t5029-2003.
7. Maintenance and loading and unloading shall meet the requirements of SY/ t5643-1995.
8. Salt spray test does not change color for 96 hours.
9. The artificial seawater immersion method does not change for 60 hours.
