Ni–Fe–W alloys were obtained by electroplating using an ammoniacal citrate bath with a cation exchange membrane cell. The addition of 8 atom % iron to the Ni–W alloy (Ni78Fe8normalW14) removed surface microcracks on the deposits and increased the iron content, which was paralleled by an apparent increase in the tungsten content. To improve the microhardness, deposits were heat-treated at various temperatures. The maximum Vickers hardness value of 1350 was obtained after heat-treatment at 500°C . X-ray diffraction analysis revealed that the increasing annealing temperature induced both grain growth and precipitation of new phases, especially NiWO4 . Transmission electron microscopy and selected area diffraction observations revealed that annealing at 500°C led to a significant hardening of the deposits due to the precipitation of new phases with nanosized grains. However, as the annealing temperature was increased above 500°C , the microhardness began to fall with increasing grain size.

No abstract

An energy-based crack-growth model was developed in this study to simulate the propagation of top-down cracking in asphalt pavements. A viscoelastic fracture mechanics approach, the generalized J-integral, was employed to model the crack growth of asphalt concrete. Laboratory fatigue crack propagation tests for three asphalt mixtures were performed at various load levels, frequencies, and temperatures. Disk-shaped specimens with a proper loading fixture and crack growth monitoring system were selected for the tests. It was observed from the tests that the crack-propagation model based on the generalized J-integral was independent of load levels and frequencies, while the traditional Paris law model based on stress intensity factor was dependent on loading frequencies. However, both models were unable to deal with the temperature dependence of the mixtures. The fatigue crack propagation model proposed in this study had a good agreement between experimental and predicted crack-growth lives, an indicator that the energy-based J-integral could be a better parameter to describe fatigue crack propagation of viscoelastic materials such as asphalt mixtures.

in acetone for 5 h in order to prevent the decomposition of Ti(C 1−x N x).5 The mixtures were then dried and compacted into a disc. The compaction pressure was 15 kg cm−2 to form a carbide skeleton. As an infiltrant, Ni powders were component Ti(CN) cermets', PhD thesis,

In order to reduce carbon dioxide (CO2) emissions and produce an eco-friendly construction material, a type of concrete that uses a minimal amount of cement, yet still retains equivalent properties to ordinary cement concrete, has been developed and studied all over the world. Hwangtoh, a type of red clay broadly deposited around the world, has traditionally been considered an eco-friendly construction material, with bonus advantages of having health and cost benefits. Presently, Hwangtoh is not commonly used as a modern construction material due to properties such as low strength and high rates of shrinkage cracking. Recent studies, however, have shown that Hwangtoh can be used as a mineral admixture to improve the strength of concrete. In addition, polyethylene terephthalate (PET) fibers recycled from PET bottle waste can be used to control shrinkage cracks in Hwangtoh concrete. Therefore, in this study, performance verification is conducted on newly developed Hwangtoh concrete mixed with short recycled PET fibers. The results show that Hwangtoh concrete has compressive strength, elastic modulus, and pH properties that are similar to these features in ordinary cement concrete. The properties of carbonation depth and creep strain of Hwangtoh concrete, however, are larger and smaller, respectively, than in ordinary cement concrete. According to flexural tests, reinforced concrete (RC) specimens cast with Hwangtoh admixtures (with and without PET fibers) possess similar or better capacities than ordinary RC specimens. The addition of PET fibers significantly improves the structural ductility of RC specimens under normal environmental conditions. However, the implementations of the concrete in aggressive environment must be carefully considered, since a previous study result indicates degradation of its durability performance in aggressive environments, such as seawater [1]. The results of this study validate the possibility of using eco-friendly Hwangtoh concrete reinforced with recycled PET fibers as a structural material for modern construction.