Improvement of the reinforcements distribution in the composite matrices using powder coating process

Walid Daoush, Byung K. Lim, Hee S. Park, Sayed F. Moustafa, Soon H. Hong

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review


Composite material is a tailor-made material which provides extraordinary flexibility to design the required properties to suit an application. Density and homogeneity of the composites are very important factors in the engineering applications because in-homogeneity and residual pores are harmful to the mechanical and physical properties of the composites. However, when using the conventional powder metallurgy route, the interfacial bonding of matrix and reinforcements proves to be weak due to their mutual insolubility and/or non-wetability, which results in low density, high porosity content, and segregation of reinforcements. Several alternative processing techniques have been researched to develop composites through hot isostatic pressing and liquid phase sintering. Although these techniques could overcome the problem of low density, they failed to solve the problem of in-homogeneity. Composite coatings improved properties of composites heavily dependent on the nature and content of reinforcements in the coatings. The most important point is to obtain continuous, uniformly-distributed and dense-coated metal layer. Otherwise, the layer with voids or gaps may weaken, even destroying the integration between the reinforcement and the matrix. There are many advantages of the coating technique of the powders such as improvement the homogeneity and better distribution of reinforcement materials within matrix, increasing the density and good interfacial bonding, capability of using fine powders, possibility of using small alloying addition in a more uniform manner (e.g. grain growth inhibitors and micro-alloying), enhancing wetability between reinforcement and molten or semi fusion matrix, and finally adjusting the densities between blended powders to enhance mixing and powder distributions. There are only a few methods that can be used for coating (encapsulating) reinforcement powders such as electrolytic deposition, electroless deposition, molten salts method, and mechanical alloying. This work aims at improving the interfacial bonding between the metal matrix and the reinforcements phase. Several kinds of reinforcements were used as metallic or ceramic powders in the form of particles metallic or non-metallic, fibers, short fibers, and carbon nano-tube were coated by metallic or ceramic layers using the electroless deposition, electrolytic deposition, molten salts method, and mechanical alloying processes to enhance the bonding between the matrix and the reinforcement phases as well as to increase the distributions and the homogeneity of the reinforcements in the matrix. The achievement of this work are the enhancement and improvement of the properties of the products produced by traditional powder technology routes such as gears, brushes for applying to in the automotive industry, heat sink materials, and reinforced polymers for applying to the electronic industry.

Original languageEnglish
Title of host publicationHigh Performance Coatings for Automotive and Aerospace Industries
PublisherNova Science Publishers, Inc.
Number of pages24
ISBN (Print)9781608765799
StatePublished - 2010
Externally publishedYes


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