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研究生:彭坤增
研究生(外文):Peng Kun Tseng
論文名稱:銅模鍍鎳層組織及性質受熱潛變之研究
論文名稱(外文):Structure and Properties of Ni Electrodeposited Copper Mold Upon Annealing
指導教授:林招松林招松引用關係
指導教授(外文):Chao-Sung Lin
學位類別:碩士
校院名稱:大葉大學
系所名稱:機械工程研究所
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:1998
畢業學年度:86
語文別:中文
中文關鍵詞:銅模鍍鎳
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  • 被引用被引用:4
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報廢銅模的金相分析發現銅模破損機構因其位置而異:澆鑄面處呈網狀裂紋;出模口處則是嚴重磨耗導致銅模的裸露並伴隨著鎳層與銅模間的剝離。造成網狀裂紋的主要因素為熱疲勞應力,而鎳層於高溫時組織的粗化導致其硬度下降則是造成鎳層過度磨耗的主要因素。本研究主要目的,即是探討不同電鍍條件對鎳層組織與硬度的影響,再探討各組織在高溫時組織與硬度的變化情形,期能找出電鍍參數與鍍層高溫軟化的關係,同時探討高溫時鎳層與銅模間附著性的變化。變化電鍍操作參數有電流密度、鍍液PH值與鍍液溫度。鍍鎳銅模性質評估包括微小硬度、內應力、界面剪力強度。鎳層組織分析則有光學顯微鏡作結晶形態觀察、X射線繞射的優選結晶方向分析、和以 穿透式電子顯微鏡作鎳層結晶形貌、缺陷與析出物的觀察和分析。實驗結果發現,( 1)電流密度低(0.5)時鍍層原始硬度高,鍍層硬度高是因鍍層內的缺陷與雙晶多所致 。當鍍鎳層受熱後,鍍層軟化,但在熱處理溫度300∼400℃之間時,鍍層硬度急速下降,此現象乃因鎳的再結晶所影響,晶體結構的轉變從柱狀晶轉換成等軸晶,且等軸晶體隨熱處理溫度的升高(600℃)而變大。(2)當鍍液溫度(50,60℃) 時鍍層原始硬 度高;鍍液溫度(30,40℃) 時鍍層原始硬度較低。在300∼400℃之間,鍍層硬度急 速下降,晶體仍維持柱狀晶結構,只是使柱狀晶體的兩側邊從較小柱狀晶的變得較寬的柱狀晶。(3)PH值在起始的硬度上雖有差異,但在熱處理溫度300∼400之間時,鍍 層硬度急速下降,且鍍層從柱狀晶轉變成等軸晶,雖然PH值在3.0∼3.5製備的鍍鎳層於400℃加熱1小時後呈現等軸晶攙雜著小的柱狀晶的結構,但隨熱處理溫度的升高(600℃)時,等軸晶體變大而柱狀晶消失,硬度亦隨之下降。界面剪力量測發現剛鍍完 試片和熱處理後試片其破斷處皆發生在銅底材。本研究已粗略建立一套技術對未來實驗室開發出的鍍面銅模產品在上線使用前先作完整的評估。所穫得資料可協助修正電鍍製程與評估銅模壽命,所建立的各項技術,可作為開發高品質鍍面銅模的基礎。
Various types of failure were observed on the metallography specimens prepared from used Ni-electroplated Copper mold with star-like cracks presented at the region around meniscus and with the exposure of Cu and the decohesion of Ni layer at the exit end which was suffered to excessive wear.The rmal fatigue resulted in the development of star-like cracks.The coarsening of Ni layer caused the decrease of Ni deposit hardness which in turn resulted in the excessive wear. This study aims at establishing the "processing-structure-properties" of electroplated Ni deposit. The structure and properties of various Ni deposits after annealing were also investigated so that the electroplating parameters to prepare the Ni deposit with betterhigh-temperature performance can be made. Furthermore the adhesion of Ni deposit to Cu was measured with emphasis on the effect of annealing treatments. Current density, PH value and temperature of electrolyte were the major plating parameters studied. Properties of Ni deposit were measured via micro-hardness, internal stress and interfacial shear strength. Microstructural characterization of Ni deposit was performed using optical microscopy, X-ray pole figure measurement and cross-sectional transmission electron microscopy.It is found that the relatively-harder Ni deposit plated at0.5 A/dm2 is associated with the highly-dislocated defects and twins. Hardness of Ni deposite decreases gradually with annealing temperatures of less than 300 oC. A dramatic decrease in Ni deposit hardness occurred while the annealing temperatures go from 300 to 400 oC, indicating recrystallization of Ni deposit takes place with this temperature range. At the same time, the columnar grains of Ni deposit evolved into equi-axed grains with an increasing average grain size with annealing temperature. Ni deposits made from 50 or 60 oC electrolytes exhibit higher hardness than those plated at 30 or 40 oC electrolytes. Unlike the Ni deposits made from 50 or 60oC which consisted of fine equi-axed grains after annealing above 500 oC,the Ni deposits plated at 30 or 40 oC electrolytes still retained their columnar grain structure even after 600 oC annealing. Although the Ni deposits plated at various PH values have different hardness, the hardness of each Ni deposit decreases abruptly once the annealing temperature is higher than 300 oC. Ni deposits plated from electrolytes of PH values of 3 or 3.5 consist of a mixed columnar and equi-axed grain structure after 400 oC annealing. After 600 oC annealing the Ni deposits exhibit an equi-axed grain structure. During the measurement of interface shear strength fract ure occurred within Cu substrate for both as-deposited and annealed Ni-plated Cu. A systematic procedure has been established to assess the in-laboratory performance of Ni-electrodeposited Cu mold. The techniques established and the findings of this study provide a basis for Ni electrogalvanizers to modify the electroplating parameters for plating Ni deposits with better performance or to develop the new products of better performance.
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