Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/9536
標題: 鎳鋁介金屬化合物硬面銲覆性質之研究
The Study of Hardfacing Properity of Nickel Aluminum Intermetallic Compound
作者: 謝媛晰
HSI, HSIEH YUEN
關鍵字: Hardfacing;硬面銲覆;Nickel Aluminum Intermetallic Compound;GTAW;鎳鋁介金屬化合物;鎢極電弧惰性遮護
出版社: 材料工程學研究所
摘要: 
摘要
鎳鋁介金屬化合物具有高強度、高硬度、質量輕、耐氧化、耐腐蝕及低磨耗係數等特點,因此為當前最具潛力的材料之一。若能以硬面處理的方式將鎳鋁介金屬被覆於物體表面,不但可提高工件使用壽命、節省製造維修費用外、還可減少修理和更換磨損工件的時間。
本文以鎢極電弧惰性遮護硬面銲覆的方式,將不同鎳鋁合金配比之銲料,銲覆於S45C中碳鋼基材上。藉由金相組織分析、硬度測量及X 光繞射等方法分析銲覆層組織,並進行乾砂磨耗、環對盤磨耗試驗,評估不同鎳鋁合金配比之銲覆層的抗磨耗性能,再利用掃描式電子顯微鏡觀察磨耗表面。
實驗結果發現有橫越並貫穿銲覆層的巨觀裂縫;而熱影響區都是沿著晶界龜裂的現象產生,而此情形會因為鎳含量的增加而趨於緩和。不同鎳鋁合金配比之銲覆層組織為常見的銲後樹枝狀晶組織,銲覆層結構經XRD分析,主要為β-NiAl相、β-AlFe相、α´-Ni3Al相、δ-ferrite,當鎳鋁比增加到2:1時出現了少量的α´-Ni3Al相,而隨著鎳含量的增加,銲覆層產生α´-Ni3Al的相也就隨之增加。
經由銲覆後表面硬度值皆有提升的現象,而由原本的β-NiAl相,隨著鎳含量的增加而讓β-NiAl相的基地中產生穩定的α´-Ni3Al相,使得剛好藉由α´-Ni3Al相來強化NiAl相晶界而改善NiAl室溫延展性不佳的問題,故使得延展性增加而硬度值降低。

Abstract
Ni-Al intermetallic compound (IMC) has excellent characteristics such as high strength, high hardness, light weight, anti oxidation, anti corrosion and low wear coefficient. It's one of the materials with high potential. If Ni-Al intermetallic compounds were coated on the surface of an object by using hardfacing treatment, it can not only extend life of specimen but also reduce the time for service and component replacing.
The study taking advantage of GTAW to weld on S45C steel with five Ni-Al specific composition powder filler. In order to inverstage the properity of the hardfacing layer, microstructure was observed by an optical and scanning electron microscope. For phase identify X-ray diffraction technique was used. At last, sand abrasion and ring on disc abrasion was done for knowing the difference type abrasion resistance.
The result shows that macro crack cross through the hardfacing layer. In heat affect zone were intergranular cracks. The crack will be reduced with the increase of nickel addition. The most microstructure of the hardfacing is dendrite structure. The coating surfaces of different Al and Ni ratio have β-NiAl, β-AlFe, α´-Ni3Al and δ-ferrite phases were discovered by XRD analysis. As the ratio of Al-Ni increases up to 1:2, it contains few amounts of α´-Ni3Al phase. With the increasing of nickel addition, the α´-Ni3Al phase also increased.
By the mechanical property test, the surface hardness will increased by using after hardfacing treatment. As nickel increasing, the α´-Ni3Al will appear in the β-NiAl matrix. The α´-Ni3Al will strengthen the grain boundary of NiAl to improve ductility at room temperature.
URI: http://hdl.handle.net/11455/9536
Appears in Collections:材料科學與工程學系

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