Tribological and mechanical properties of Zirconium Di-boride (ZrB₂) particles reinforced aluminium matrix composites

Abstract

In the last few decades, the interest of using the metal matrix composites (MMCs) has enhanced owing to its potential for replacing the traditional materials in several industrial applications. In this articles, a state of the art review on Zirconium Di-boride (ZrB₂) particles reinforcement aluminium matrix composites. This review paper exhibits the mechanical and tribological properties of ZrB₂ particles reinforced aluminium matrix composites. Mostly the ZrB₂ particles based composites are prepared by in situ casting technique and the very few research works are done in other processing technique. Generally the properties of the composites are increased with the increase in ZrB₂ particle content.

Introduction

During the past two decades, materials design has transferred emphasis to pursue light weight, environment friendliness, low cost quality, superior service temperature, enhanced elastic modulus and enriched wear resistance and performance. The foremost objectives of using composite materials is the advantage of attaining property combinations that can result in a number of service benefits. Ceramic particulates incorporated aluminum matrix composites (AMCs) are a new generation of metal matrix composites which have the potential of sustaining the emerging demand for advanced engineering applications. These expects were fulfilled owing to enormous mechanical and tribological properties of the aluminum matrix composite. Generally in automobile, transportation, marine, structural, defence and aircraft applications require an alloy material which proposes improved specific strength, stiffness, toughness, wear and corrosion resistance [1], [2], [3].

The most widely employed composite matrix materials are magnesium, aluminium, zinc and titanium and the typical reinforcements are Titanium carbide (TiC), Silicon carbide (SiC), Boron carbide (B₄C), Zirconium Oxide (ZrO₂), Titanium oxide (TiO₂), Aluminium Oxide (Al₂O₃), Silicon Oxide (SiO₂), Silicon nitride (Si₃N₄), Boron Nitride (BN), Titanium diboride (TiB₂) and Zirconium diboride (ZrB₂) etc., [4], [5], [6], [7]. Zirconium diboride (ZrB₂) is a naturally inherent reinforcement material for aluminium based composites as it possesses the effective combination of physical and mechanical properties like high melting point, superior hardness, low density, high elastic modulus and outstanding wear resistance. Especially utilization of ZrB₂ particles as reinforcement has always improved the mechanical properties of AMCs [8], [9].

Liquid route of processing embraces either incorporating ceramic particles externally to the molten metal or synthesizing in the melt itself. The former is known as ex-situ fabrication (stir casting, squeeze casting and spray deposition) as discussed earlier while the later is called as in situ fabrication. In a furnace the matrix alloy is melted. The measured quantity of reaction elements/compounds is added into molten matrix material to synthesize reinforcements. Stirring is then continued for some time to disperse reinforcements uniformly into the matrix. Stirring should not be vigorous as done in stir casting which will lead to entrapment of floating reaction products into the matrix alloy. The composite melt is poured into moulds after removing the reaction products i.e., slag. In situ fabrication is a single step economical process. In situ method overcomes the limitations of stir casting process such as improper wetting of reinforcement particles and density dependency of particles and its associated problems like sinking and floating of particles. The in situ techniques lead to clean interfacing, high interfacial bonding strength, uniform distribution of small particles in the matrix, thermodynamically stable particles, higher mechanical properties, and low cost processing method [10].

In the present review article, an attempt has been made to review on ZrB₂ particles based composites. The ZrB₂ particulates based composites exhibits, the rise in ZrB₂ contents tends to enhance the hardness, tensile strength and the wear resistance of the AMCs.