Metallic Ag as the second phase was added into PZT ceramic matrix to fabricate piezoelectric composites and functionally graded actuators by gradually altering Ag concentration, aimed to improve mechanical properties and to solve possible interfacial debonding usually observed in conventional bimorph-type piezoelectric actuator. The PZT/Ag composites were obtained by directly co-firing PZT and Ag powders at 1200 • C for 1 h. The fracture strength σ f and fracture toughness K I C , as well as the corresponding piezoelectric properties, were firstly evaluated upon the PZT/Ag composites for Ag concentrations of 0-30 vol%. The mechanical properties for the PZT/Ag composites were found to be greatly enhanced compared with pure PZT ceramics: from 69 to 129 MPa for σ f and from 1.0 to 3.7 MPa.m 1/2 for K I C . With increasing Ag concentration, the piezoelectric constant d 33 of PZT/Ag composites was found to decrease from 419 to 86 pC/N. Then, a functionally graded actuator was fabricated and evaluated in terms of electric-induced curvature k. The PZT/Ag FGM actuator with size of 12 mm × 3 mm × 1 mm has a curvature k of 0.03-0.17 m −1 that corresponds to applied voltages of 100-500 V. A comprehensive comparison was made on the mechanical property enhancements by the metal particles dispersion, and the bending displacements produced by the FGM actuators between the PZT/Ag and previously fabricated PZT/Pt systems.

Aluminum matrix composites with nondirectional graphite-flake reinforcement were fabricated by hot-press sintering. To avoid interfacial reactions in the graphite-flake-reinforced composites, copper (Cu), with a thickness of approximately 50 lm, was coated on the graphite flakes by chemical plating. The results show that the Cu is uniformly distributed on the surface of graphite flakes. The thickness of the Cu plating is in the range of 15.3-21.2 lm. For volume fractions of the nondirectional graphite flakes ranging from 40% to 70%, the Al/Cu-plated graphite-flake (Cu-GF) composites display thermal conductivities from 328 W/m K to 612 W/m K. The theoretical values calculated by the parallel alternate layer model are slightly higher than the experimental values. The friction coefficient (0.171) and wear rate (2.31 9 10 À7 mm 3 /N mm) of the composites with 70% Cu-plated graphite flakes are the lowest of the compositions observed in this study. Owing to the lubrication of graphite, the friction coefficient and wear rate decrease with increasing graphite flake content. The thermal conductivity and wear resistance gradually increase when the volume fraction of the Cu-plated graphite flake increase.

Very few industrial processes only produce the target product, but other materials not desired by the manufacturer are also obtained. These unwanted products constitute the residues of the processes and their discharge contributes to the overall environmental impact. The concept of preventing pollution is gaining increased importance, and certain industries that are particularly similar in nature, could benefit from PPP (Pollution Prevention Program) cross-fertilization. Implementing PPP sets important targets and benefits. A number of codes of good practice lead to PPP, both from a management and technical viewpoints. The fast development of technology and pollution standards implies important challenges for environmental engineers, environmental research and development. Although there is no general route to success, there are however a number of pollution prevention and waste reduction schemes that apply. These alternatives and procedures are illustrated in the paper. It is clear that environment-caring companies will be more readily accepted by their human environment. It is also evident that the engineer of the 21st century faces new and complex environmental challenges. Research remains the backbone of successful development.

AZ31B Magnesium alloy sheets with about 1 mm in thickness were rolled by one pass and several passes from the extruded ingots with different thickness. The effects of processing variables on microstructure and mechanical properties of AZ31B Mg alloy sheets were investigated. XRD indicated that AZ31B magnesium alloy sheets have a dominant texture with (000l) orientated plane. The large deformation results in the formation of fine and homogeneous microstructure due to the recrystallization during extruding and hot-rolling. The thinnest sheet rolled by several passes showed equiaxed grains with 5-10μm in diameter. The fine recrystallization grains contribute to the increase in the corrosion resistance. The corrosion rate of the sheets rolled by several passes was 1.9 mm/year in 3.5% NaCl solution.