Excellent thermal conductivity and lower density make Al–Si alloys a suitable alternative for cast iron in the fabrication of engine components. The increase in the maximum operation temperature and pressure of engines necessitates improving the thermomechanical fatigue performance of Al–Si alloys. This paper has two major parts focussing on the use of Al–Si based alloys in cylinder heads and engine blocks.In the first part, the structural stress–strain and material property requirements of cylinder heads are discussed. In addition, the physical and mechanical properties of different competing materials used in the manufacture of engine components are reviewed. The physical metallurgy, solidification sequence and thermal conductivity of Al–Si based alloys are reviewed. Also discussed is the effect of microstructural features on thermomechanical fatigue lifetime. This part also includes an overview of the strengthening mechanisms of cast Al–Si alloys, by dispersed phases and heat treatment.Demands ...

Application of cast Al–Si alloys in internal combustion engine components

The rapidly expanding toolbox for design and preparation is a major driving force for the advances in nanomaterials science and technology. Melt infiltration originates from the field of ceramic nanomaterials and is based on the infiltration of porous matrices with the melt of an active phase or precursor. In recent years, it has become a technique for the preparation of advanced materials: nanocomposites, pore-confined nanoparticles, ordered mesoporous and nanostructured materials. Although certain restrictions apply, mostly related to the melting behavior of the infiltrate and its interaction with the matrix, this review illustrates that it is applicable to a wide range of materials, including metals, polymers, ceramics, and metal hydrides and oxides. Melt infiltration provides an alternative to classical gas-phase and solution-based preparation methods, facilitating in several cases extended control over the nanostructure of the materials. This review starts with a concise discussion on the physical and chemical principles for melt infiltration, and the practical aspects. In the second part of this contribution, specific examples are discussed of nanostructured functional materials with applications in energy storage and conversion, catalysis, and as optical and structural materials and emerging materials with interesting new physical and chemical properties. Melt infiltration is a useful preparation route for material scientists from different fields, and we hope this review may inspire the search and discovery of novel nanostructured materials.

Melt Infiltration: an Emerging Technique for the Preparation of Novel Functional Nanostructured Materials

Corrosion of stainless steel coated with TiN, (TiAl)N and CrN in aqueous environments

This research studied the corrosion resistance enhancement of AISI 304 stainless steel by utilizing TiCN, CrN, and DLC films deposited by means of physical vapor deposition (PVD). The corrosion media used were NaCl, HCl, and H 2 SO 4 aqueous solutions, respectively. The results showed that all PVD coating types reduced the corrosion current thus providing better corrosion resistance. Among the three PVD films studied, DLC film gave the best results in all aqueous solutions. CrN film yielded a better corrosion resistance than TiCN in H 2 SO 4 solution, although both produced about the same effect in HCl and NaCl solutions.

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Effects of PVD sputtered coatings on the corrosion resistance of AISI 304 stainless steel

Arc-evaporated CrN, CrN and CrCN coatings

Effect of substrate surface roughness on the characteristics of CrN hard film

Effect of austempering heat treatment on fracture toughness of copper alloyed gray iron

Titanium is an anti-spheroidizing element and also carbide former in ductile iron. On the other hand, increasing the casting size essentially lowers the cooling rate that opposes the chilling tendency of titanium. This research was to study the combined effects of titanium and section size on their promotion of compacted graphite (CG) formation, and at the same time how matrix constituents were altered in heavy-wall castings. It was found that at the increasing casting thickness of 30 mm, 65 mm and 80 mm, the percentage of CG increased while that of pearlite decreased either with or without titanium addition. However, titanium (added in an amount of 0.15 wt%) effectively promoted the formation of CG by over 10% and at the same time increased the pearlite content in the matrix. This was especially true in the thinner 30 mm casting. Irons with titanium addition exhibited a bit lower Brinell hardness, elongation, and impact toughness due probably to the higher CG percentage that facilitated easier crack propagation. However, comparing to the un-alloyed iron, fracture toughness increased along with tensile strength for iron with titanium addition in all casting sizes of 30–80mm. The higher pearlite content in the matrix has overridden the effect of increased CG percentage such that tensile strength and KIC value both increased.

Effects of titanium addition and section size on microstructure and mechanical properties of compacted graphite cast iron

Study of high cycle fatigue of PVD surface-modified austempered ductile iron

This research applied rapid induction heating and water quenching cycles to study the thermal shock resistance of high-nickel austenitic cast irons. Both flake graphite (FG) and compacted graphite (CG) cast irons were evaluated. In addition, alloying of cobalt and (Cr + Al) to the high-nickel base materials was performed to produce ultralow thermal expansion and hightemperature specialty irons. Microstructural analysis, as well as mechanical and thermal properties testings, was performed to find out the relationship among microstructures, properties, and thermal shock resistance of the materials under investigation.

Shen-Chih Lee

Papers

Effect of substrate surface roughness on the characteristics of CrN hard film

Effect of austempering heat treatment on fracture toughness of copper alloyed gray iron

Effects of titanium addition and section size on microstructure and mechanical properties of compacted graphite cast iron

Study of high cycle fatigue of PVD surface-modified austempered ductile iron

On thermal shock resistance of austenitic cast irons