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Investigation On Fabrecation,Structures And Properties Of W(Nb)Cu Alloy

Posted on:2017-05-17Degree:MasterType:Thesis
Country:ChinaCandidate:Z C QinFull Text:PDF
GTID:2381330596479856Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
WCu alloys as core components are widely used in high voltage and ultra high voltage electrical switch.The alloy,as a composite with excellent performance,is composed of tungsten with high melting point,high density and low expansion coefficient and copper with high electrical conductivity and high thermal conductivity.At present,as China's economy grows rapidly,the demand for electricity is still on the rise.According to "13th Five-Year Plan",the average growth rate for power consumption will be 5.5%,about 7.4 trillion degrees,by 2020 year.In order to create efficient,intelligent and secure modern new power system,the performance and service life of WCu contact materials have been put forward to higher requirement.So manufacturing excellent commercial WCu alloy with good performance and long service life will be a direction for us to pursue.In this paper,we manufacture the W(Nb)Cu alloy by adding Nb to WCu alloy and the effects of different sintering methods,sintering temperatures,the element contents on the microstructure and properties have been discussed.Then the properties of the optimal W(Nb)Cu alloy under the simulating actual conditions have been tested.The results are as follows:(1)High energy ball milling can effectively refine W,Nb and Cu powders,making the microstructure uniform and can promote the W-Nb,W-Cu alloying.Tungsten particles in the W(Nb)Cu alloy prepared by the hot-pressed sintering perform multiple scales in size,making a good contribution to microstructure and performance.(2)The densification rate of W(Nb)Cu alloy increase linearly with pressing temperature during th e hot pressing process.But the morphology did not change significantly.With the sintering temperature increasing,the sintering-necks between tungsten particles and the interconnection of tungsten skeleton perform well,leading to a higher strength with low conductivity.(3)With copper content increasing,the tungsten particles refined significantly and the copper phase enriched seriously in the W(Nb)Cu alloy.Wh en the copper content is 30wt.%,the alloy has a uniform microstructure and a better interconnection tungsten skeleton.When the niobium content is 0,the size of tungsten particles is larger,showing a scattered distribution in the alloy.When the niobium content is 3wt.%,it is helpful for tungsten particles to contact,growth and merge,which can provide a good interconnection of the tungsten skeleton making the alloy have a higher strength.When the niobium content is more than 3wt.%,the tungsten particles have higher tendency to reunite and more copper-rich regions occur in the W(Nb)Cu alloy.(4)The W(Nb)Cu alloy with 30wt.%copper content and 3wt.%niobium content,which is pressed at 1060? and sintered at 1240?,owns excellent relative density(98.89%),hardness(395HB)and conductivity(10.2MS/m).Under the simulating actual conditions,compared with the WCu alloy without niobium,the W(Nb)Cu alloy has higher and more stable electrical breakdown strength and better resistance to room temperature fatigue and abrasion.
Keywords/Search Tags:W(Nb)Cu alloy, Hot-pressed sintering, High energy ball milling, Electrical breakdown, Fatigue and abrasion
PDF Full Text Request
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