利用原生TiC強化複合工具鋼

Strengthening of Composite Tool Steels by Self-Synthesized TiC

邱筱菁(Hsiao-Jing Chiu)

指導教授 ： 陳貞光

國立臺北科技大學/工程學院/材料科學與工程研究所/碩士(2009年)

摘要

TiC作為增強相添加於工具鋼等金屬基材，得以提升金屬基複合材料(MMCs)之磨耗性及強度等機械性質。本研究嘗試利用機械合金法使Ti與奈米碳粉在遠低於傳統製程溫度下，以行星式球磨使原料粉末在固態反應製備原生TiC。研究結果顯示，Ti-50at.%C混合粉末以轉速400 rpm及球磨時間8小時以上，球磨能量累積達到足以反應時，Ti與C以機械誘發自蔓延反應(MSR)瞬間大量生成TiC，成功製備細緻且球形的原生TiC粉末。本研究以真空燒結與熱均壓製程製備工具鋼-TiC複合材料，並探討基地相經由球磨處理後對於增強相分佈與機械性質之影響。實驗結果顯示，真空燒結後之試片其相對密度可達到98.7%以上，接著經由熱均壓後，緻密性可進而提升至99.9%以上。經球磨後的工具鋼粉能夠有效提升TiC分散的效果，並與TiC產生良好的結合，即使TiC添加量高達44 vol.%，其在基地相中的分佈情形仍相當良好。燒結體經由熱均壓處理後可提升硬度與抗彎強度，添加44 vol.%TiC的複合工具鋼經由熱均壓處理，可得到最高硬度值71.6 HRC，而抗彎強度值則受到碳化鉻析出與孔隙率之綜合影響，隨TiC含量上升略微下降。

關鍵字

原生TiC ； 機械合金法 ； 工具鋼 ； 金屬基複合材料 ； 熱均壓

並列摘要

TiC is often used as reinforcement phase to improve wear-resistant properties and hardness of tool steels and metal matrix composites (MMCs). In present study, synthesized TiC is formed via mechanical alloying (MA) by planetary ball milling Ti and carbon black powders. It is observed that very fine and spherical in-situ TiC powders can be synthesized by high energy ball milling at the condition longer than 8 hrs at 400 rpm. These TiC and tool steel powders are then sintered by combining two powder metallurgy routes, vacuum sintering and hot isostatic pressing (HIP). HIPping is beneficial in reducing internal voids of vacuum sintered composites and thus increases composite mechanical properties. Up to 99.9% sintering density is achieved without encapsulation. It is found that the fine in-situ TiC particles distribute uniformly with the ball milled tool steel powders. The amount of TiC can be added up to 44 vol.%. And the composite such formed can achieve hardness as high as 71.6 HRC. In present study, composite tool steels containing TiC are produced by a novel process which combines in-situ and powder metallurgy techniques.

並列關鍵字

in-situ TiC ； mechanical alloying ； tool steel ； metal matrix composite ； hot isostatic pressing

參考文獻

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