The effects of ultrasonic vibration on mechanical properties of tungsten particle-reinforced copper-matrix composites

ABSTRACT

W-Cu micro-powder mixtures usually have poor sinterability due to the relatively low solubility of W in both solid and liquid Cu. In fabricating W-Cu composites, an electroless copper plating process is often used to coat Cu on the W particle surface prior to the sintering process. Due to their small size W particles tend to agglomerate during the plating process, hence the individual particle may not be properly coated with Cu. In this study, ultrasonic vibration is applied in the electroless plating process to break up the agglomerations and restrain the powders from gathering, ensuring a uniform deposition of the Cu on individual W particle. W-Cu composite samples containing pure Cu and 6, 9 and 12 wt-% of Cu-coated W particles, respectively, are fabricated using a standard powder metallurgy technique. It is shown that the application of ultrasonic vibration in the activation and deposition steps of the electroless copper plating process prevents W powder agglomeration and ensures that each W particle is coated with Cu. As a result, the mechanical properties of the W-Cu composites are significantly improved. It is found that the optimal tensile strength and yield strength are obtained using a W reinforcement phase content of 9 wt-%.

RÉSUMÉ

Les mélanges de poudres microscopiques de W et Cu ont habituellement un frittage médiocre en raison de la solubilité relativement faible du W tant dans le Cu solide que liquide. Par conséquent, en fabriquant des matériaux composites de W et Cu, on utilise souvent un processus de placage de cuivre autocatalytique pour appliquer un revêtement de Cu à la surface de la particule de W avant d’effectuer le frittage. Cependant, en raison de leur petite taille, les particules de W tendent à s’agglomérer lors du placage, et donc il se peut que les particules individuelles ne soient pas correctement revêtues par la poudre de Cu. En conséquence, dans l’étude actuelle, on applique une vibration ultrasonique au cours de la déposition autocatalytique afin de briser les agglomérations et d’empêcher les poudres de s’assembler à nouveau. Ceci, afin d’assurer un dépôt uniforme de la poudre de Cu sur les particules individuelles de W. On a fabriqué des échantillons composites de W et Cu consistant de Cu pur et de 6, 9, et 12% en poids, respectivement, de particules de W revêtues de Cu en utilisant une technique standardisée de métallurgie des poudres. On montre que l’application de vibration ultrasonique pour les étapes d’activation et de dépôt lors du placage autocatalytique empêche l’agglomération de la poudre de W et assure que chaque particule de W est revêtue de Cu. Par conséquent, les propriétés mécaniques des échantillons composites de W-Cu sont améliorées significativement. On a trouvé que l’on obtenait des valeurs optimales de résistance à la traction et de la limite d’élasticité en utilisant une teneur de 9% en poids de W dans la phase de renforcement.

KEYWORDS:

• Electroless plating
• ultrasonic vibration
• composite material
• powder metallurgy

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Te-Tan Liao received the BS, MS and PhD degrees in Mechanical Engineering from the National Cheng Kung University, Tainan, Taiwan, in 1983, 1988 and 2003, respectively. He is currently a Professor with the Department of Mechanical Engineering, Far East University, Tainan, Taiwan. His research interests include mechanical property of material, geometrical optics with applications to optical design and noncontact measurement, and robotics.

Chieh Kung received his PhD degree in Mechanical Engineering from University of Arizona, USA, 1991. He is an Associate Professor at the Department of Industrial Design of Far East University, Taiwan. He has gained more than 20 years of experiences in teaching and research. The areas of his research interest include product design, strength analyses, and composites.

Chun-Ta Chen received the BS and MS degrees in Mechanical Engineering from the National Cheng Kung University, Tainan, Taiwan, in 1985 and 1988, respectively, and the PhD degree in Mechanical Engineering from Case Western Reserve University, Cleveland, OH, USA, in 1996. He is currently a Professor with the Department of Mechatronic Engineering, National Taiwan Normal University, Taipei, Taiwan. His research interests include robotics with applications to biomedical engineering, dynamic analysis and control of parallel mechanisms, and virtual reality.

Additional information

Funding

The financial support provided to this study by the Ministry of Science and Technology of Taiwan under Grant No. MOST 104-2221-E-269-007 is gratefully acknowledged.