脈衝電流電鑄Ni-P鍍層之磨潤特性研究

Study on Tribological Characteristics of Ni-P Based Coatings Produced by Pulse Current Electroforming

侯光煦(Kung-Hsu Hou)

指導教授 ： 鄭銘章

國立中央大學/工學院/機械工程學系/博士(2007年)

摘要

本研究藉由脈衝電流電鑄技術，發展Ni-P合金鍍層及Ni-P-SiC複合鍍層的製備，並於常溫、不同昇溫(100~300℃)及無潤滑條件下對其進行磨潤實驗研究。研究結果發現脈衝電鑄Ni-P鍍層的內應力遠低於直流電鑄的Ni-P鍍層；分析發現甫鍍製高磷含量(P > 8 wt.%)之Ni-P電鑄層，其硬度隨著磷含量的增加而降低，隨磷含量的增加，鍍層結構由微結晶態逐漸轉變為X-ray非晶態。常溫磨耗試驗及分析顯示：甫鍍製Ni-P鍍層之磨耗阻抗隨鍍層硬度增加而增加；硬度為主要影響磨耗阻抗的主要性質，甫鍍製Ni-P鍍層磨耗阻抗最高可達Ni鍍層的11倍。經400℃熱處理之Ni-P鍍層存在硬質Ni3P相的析出，此可進一步降低鍍層的磨耗率；熱處理鍍層的磨耗阻抗最高可提昇為甫鍍製鍍層的2.5倍。甫鍍製及熱處理鍍層的磨耗阻抗及硬度均隨晶粒尺寸增大而增加；亦即高磷Ni-P鍍層的強度與晶粒尺寸呈現逆轉Hall-Petch 關係。於溫度100~300℃的磨耗試驗顯示，甫鍍製(P: 8.7wt.% ~13.9wt.%)Ni-P鍍層的磨耗阻抗隨溫度昇高而增加。
在Ni-P-SiC 複合鍍層的研究上，採用0.3μm 的碳化矽微粒引入鍍液中，顯示鍍層之磷含量隨鍍液中的碳化矽微粒濃度增加而降低，且鍍層中沉積之SiC微粒含量隨鍍液中碳化矽濃度增加而增加。脈衝電鑄鍍層之SiC微粒含量為0.2 - 1.5 wt.%高於直流電鑄鍍層之SiC微粒含量0.2 - 0.5 wt.%。磨潤研究顯示脈衝Ni-P-SiC鍍層之耐磨性優於直流Ni-P-SiC電鍍層，且於相同硬度條件下，Ni-P-SiC複合鍍層之磨耗阻抗優於Ni-P鍍層；相同電鑄條件下，Ni-P-SiC複合鍍層之重量磨損可較Ni-P鍍層減少62 %，而Ni-P-SiC複合鍍層的磨耗阻抗最高可達純Ni 的10倍。

關鍵字

鎳磷合金鍍層 ； 鎳磷碳化矽複合鍍層 ； 脈衝電流 ； 電鑄 ； 磨潤 ； 磨耗阻抗 ； 磨耗機制

並列摘要

In this study, attempt has been made to investigate the wear resistance of Ni-P alloy coatings and Ni-P-SiC composite coatings that manufactured by pulse current (PC) electroforming technology. The tribological tests of such plated coatings were carried out at ambient temperature, evaluated temperature(100~300℃) and without lubricants conditions. The results of this investigation showed that the internal stress of the PC-deposited Ni-P coating is much lower than that of direct current (DC) deposited Ni-P coatings. The analytical results of the high phosphorous contents (P > 8 wt.%) coatings indicate that increasing the phosphorus content in the layer reduces the hardness of the Ni-P electroformed coatings, and the gradually leading to the coatings structure from micro-crystalline transform to X-ray amorphous.
Wear test results of as-plated Ni-P coatings under normal temperature show that the wear resistance of Ni-P alloy layers increases with the hardness of the coatings. The hardness primarily affects the wear resistance of the Ni-P as plated coatings; and the optimum wear resistance of Ni-P coatings can reach 11 times that of Ni coatings. After heat-treatment that would be enhancing the strength of the Ni-P coatings and leads to a lower wear rate for heat-treated coating. The wear resistance of heat-treated coating can be as high as 2.5 times that of as-plated coating. In addition, the wear resistance and hardness increases with the increasing of grain size for both as-plated and heat-treated coatings. It suggests that the strength and grain size of the Ni-P coating with high phosphorus content obeys the inverse Hall-Petch relationship. Under evaluated temperature saturation, the wear tests show that the wear resistance of the as-plated Ni-P (P: 8.7wt.% ~13.9wt.%) coatings was increased with temperature increased.
In the Ni-P-SiC composite coatings, the study attempted to incorporate 0.3μm SiC particles into a Ni-P alloy matrix by pulse current (PC) and direct current (DC) plating. Both plating methods showed that the phosphorus content in the deposit falls with increasing SiC content in the bath, and that the SiC content in the composite coating rises with rising SiC content in the bath. The pulse plating deposit with SiC particles 0.2 - 1.5 wt.% was higher than direct current plating with SiC particles 0.2 - 0.5 wt. % in deposits. The wear-proof shows that the tribological behavior of Ni-P-SiC of the PC plating is better than that of the DC plating deposit. At normal temperature, experimental results show that the wear resistance of Ni-P-SiC composite coatings is superior to Ni-P composite coatings if under the same level of hardness. The wear weight loss of Ni-P-SiC composite coatings is even about 62% less than that of Ni-P composite coatings, in which is based on the same produced condition. Further more, both the hardness and wear resistance of Ni-P-SiC composite coatings are superior to pure Ni coating, wherein its wear resistance is even up to 10 times better than the pure that of Ni coating.

並列關鍵字

Wear mechanism ； Wear resistance ； Tribology ； Ni-P alloy coatings ； Ni-P-SiC composite coatings ； Pulse current ； Electroforming

參考文獻

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