C. Garrard

Bio: C. Garrard is an academic researcher from Defence Science and Technology Organisation. The author has contributed to research in topics: Corrosion & Pitting corrosion. The author has an hindex of 1, co-authored 1 publications receiving 53 citations.

The corrosion behaviour of aluminium-silicon carbide composites in aerated 3.5% sodium chloride

Abstract: The corrosion behaviour of aluminium 6061-T6 alloy and 6061-SiC composite in 3.5% NaCl was investigated. While alloy 6061 underwent pitting corrosion, the composite material exhibited two types of corrosion: (1) pitting and crevice attack around each SiC fibre, and (2) crevice corrosion in surface voids or hair-line fractures. The pitting and crevice corrosion around the fibres were due to the accumulation of magnesium at the fibre-matrix interface during composite manufacture. The effect of cerium inhibition was also examined with these materials, and was shown to retard pit initiation for approximately 1–2 days.

Lanthanide compounds as environmentally-friendly corrosion inhibitors of aluminium alloys : A review

Abstract: Currently, chromates are among the most common substances used as inhibitors or incorporated in anticorrosive pretreatments of aluminium alloys. However, these compounds are highly toxic and their use produces serious environmental hazards. Consequently, an intense research effort is being undertaken to replace chromates by more ecological compounds. In recent years, several authors have begun studies of the behaviour of lanthanide compounds in the corrosion protection of metallic alloys. After a brief overview of the use of chromates and their ecological alternatives in corrosion protection systems, the paper reviews progress from the literature published to date concerning the application of lanthanide compounds as corrosion inhibitors of aluminium alloys in aqueous solution. Aspects of the mechanism involved in the cathodic inhibition process by lanthanides are also dealt with. In addition, these compounds have been used to prepare chromate-free conversion coatings by full-immersion and electrochemical activation methods. Treatments proposed for these conversion coatings are discussed in detail. From the comprehensive review presented in this article, it is concluded that lanthanide compounds fulfil the basic requirements for consideration as components of more environmentally-friendly formulations: low toxicity and acceptable protective capacity. However, methods proposed up to now present various limitations that restrict their application in practice. Further research efforts are necessary to develop feasible treatments for industry.

Metal Matrix Composites

Abstract: Metal matrix composites consist of a metal or an alloy as the continuous matrix and a reinforcement that can be particle, short fiber or whisker, or continuous fiber. In this chapter, we first describe important techniques to process metal matrix composites, then we describe the interface region and its characteristics, properties of different metal matrix composites, and finally, we summarize different applications of metal matrix composites.

Electrodeposition and mechanical and corrosion resistance properties of Ni–W/SiC nanocomposite coatings

Abstract: Ni–W/SiC nanocomposite coatings with various contents of SiC nano-particulates were prepared by electrodeposition in Ni–W plating bath containing SiC particulates. The influences of the SiC nano-particulates concentration, current density and stirring rate of the plating bath on the composition of the nanocomposite coatings were investigated. The surface morphologies of the Ni–W alloy and Ni–W/SiC nanocomposite coating were observed using a scanning electron microscope (SEM). The morphology of Ni–W/SiC nanocomposite coating is smoother than that of Ni–W alloy coating. The microhardness of composite coatings increases with the increasing content of the SiC nano-particulates in the coatings. The corrosion behavior of Ni–W alloy and Ni–W/SiC nanocomposite coatings was evaluated by the anodic polarization curves in 0.5 mol/L NaCl solution at room temperature. It shows that Ni–W/SiC nanocomposite coating has better corrosion resistance than the Ni–W alloy coating.

Corrosion inhibition of aluminum alloy AA 2014 by rare earth chlorides

Abstract: The effect of LaCl3 and CeCl3 inhibitor additions in 3.5% NaCl solution on the corrosion behaviour of aluminum alloy AA2014 has been investigated. Four different concentrations (250, 500, 750 and 1000 ppm) of LaCl3 and CeCl3 were studied. The polarization resistance increased significantly and the corrosion rate decreased by an order of magnitude with the addition of 1000 ppm of LaCl3 and CeCl3, with maximum decrease noticed for CeCl3. EIS studies showed that there was a significant increase in overall resistance after addition of 1000 ppm LaCl3 and CeCl3, when compared to the case without inhibitor. The double layer resistance and film resistance increased after inhibitor addition. Scanning electron microscopy confirmed formation of precipitates of oxide/hydroxide of lanthanum and cerium on cathodic intermetallic sites, which reduced the overall corrosion rate.

Processing issues, machining, and applications of aluminum metal matrix composites

Abstract: Aluminum metal matrix composites (AMMCs) used in different industries from automotive to aerospace for specific purposes. Many problems hinder the full-scale industrialization of AMMCs but the main problems include wettability, particle distribution, porosity, and chemical reaction. These problems have explicit effects on mechanical, wear, and corrosion resistance properties of the composite materials. Therefore, it is essential to cope up with these problems for better quality of AMMCs. This paper focuses on issues related to AMMCs fabrication, corrosion resistance, wear resistance, machining parameter optimization, and chip analysis of AMMCs. Literature provides a guideline to researchers about present scenario of AMMC fabrication using stir casting process. Moreover, paper presents properties and applications of AMMCs.