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Copper Infiltration Study On Preparation Of Tungsten Skeleton

Posted on:2010-10-28Degree:MasterType:Thesis
Country:ChinaCandidate:H B WuFull Text:PDF
GTID:2191360278969443Subject:Materials Physics and Chemistry
Abstract/Summary:PDF Full Text Request
W-Cu alloy is a good composite materials for electronic packaging ,it combine the low-expansion performance of tungsten and the high thermal conductivity properties of copper ,so it has an excellent thermal conductivity and adjustable thermal expansion coefficient . W-Cu composite is the first consideration in the military electronic device, especialy in the solid phased-array radar. However, with the development of electronic information technology, the requirements for the performance of W-Cu Materials have become higher, the production of W-Cu Materials also encountered new difficulties. In this paper, the production process of the W-Cu Materials was improved to look forward to further improving the performance of W-Cu and product rate, and reduce costs. The main thesis of this research include the selection of novel binder, the high-temperature sintering process of tungsten skeleton. Furthermore, the microstructure and the property of the composites were observed .the results are as follows:1)Stearic acid has good lubricating property and bonding property, and be able to replace the SBP plastic as binder for tungsten powder. the best dosage of stearic acid for Fine tungsten powder is 1.5%, this powder can be used for preparation of W-20Cu products; the best dosage of stearic acid for the coarse powder is 1.2%, the mixed powder can be used for preparation of W-10Cu following Products .2) two formulas are proposed for calculating the amount of stearic acid: Minimum:(?),maximum:(?)3) the empirical formula about relation between the pressure and tungsten skeleton density is proposed when stearic acid is used as binder for tungsten:4) The tungsten skeleton was slowly heated in the air to 400℃in order to remove stearic acid. The removal process has a good effect, and its residue is less than 0.05%. 5)Stearic acid is a better binder, not only homogeneous, but also improve production efficiency and reduce the security risks, basically eliminated the large holes caused by the SBP plastic.6)High-temperature sintering can significantly improve the relative density of tungsten skeleton n and W-Cu composite, 2.4μm tungsten powders sintered at 1850℃for two hours , the relative density of the tungsten skeleton is 89.82%, this skeleton can be used for preparation of W-5Cu composite, the relative density of this composite reached 99%, thermal conductivity rate is 210w ? m-1 ? k-1, airtightness is 0.6×10-9Pa ? m3 / s ,the properties meet the requirements.7)High-temperature sintering is able to remove the residual part of the carbon impurities in the tungsten skeleton. Residual carbon content of Skeleton is reduced as the sintering temperature increased, the residual total carbon content of the tungsten skeleton only is 0.0037% after sintering 2 hours at 1650℃8)Wet hydrogen sintering process can significantly lower the sintering temperature of tungsten skeleton. The volume shrinkage rate of fine tungsten powder reached 8.06% through wet hydrogen sintering 2h at 1450℃. The tungsten skeleton prepared by Wet hydrogen sintering was used to infiltrate copper and obtained the W-Cu composite with homogeneous structure, its performances achieve the requirement for heat sink materials.
Keywords/Search Tags:W-Cu composites, plasticizer, high-temperature sintering, W-skeleton, carbon analysis
PDF Full Text Request
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