Due to the rapid melting and solidification mechanisms involved in selective laser melting (SLM), CoCrMo alloys fabricated by SLM differ from the cast form of the same alloy. In this study, the relationship between process parameters and the morphology and macromechanical properties of cobalt-chromium alloy micro-melting pools is discussed. By measuring the width and depth of the molten pool, a theoretical model of the molten pool is established, and the relationship between the laser power, the scanning speed, the scanning line spacing, and the morphology of the molten pool is determined. At the same time, this study discusses the relationship between laser energy and molding rate. Based on the above research, the optimal process for the laser melting of cobalt-chromium alloy in the selected area is obtained. These results will contribute to the development of biomedical CoCr alloys manufactured by SLM.

SiO₂ aerogel powder has ultralow weight and thermal conductivity, and it cannot be easily dispersed in inorganic cementing materials (i.e., it is incompatible with inorganic cementing materials). In this study, the properties of inorganic cementing materials with hemihydrate gypsum and α-hemihydrate gypsum as main cementing materials were investigated. Moreover, the property changes resulting from the addition of SiO₂ aerogel to inorganic cementing materials were examined. Based on the obtained results, the composites of SiO₂ aerogel and inorganic cementing materials with optimal properties were prepared and investigated. The results revealed that when the composition mass ratio of the inorganic cementing material was 1:3:9:0.8 (fly ash:cement:hemihydrate gypsum:lime), the compressive strength of the cementing material was largest, reaching 7.71 MPa after 28 days of curing. Moreover, when the composition mass ratio of the inorganic cementing material was 1:3:9:0.4/0.6 (fly ash:cement:hemihydrate gypsum:lime), its softening coefficient was highest, reaching 0.97. Under the same mass ratio, the 28-day compressive strength of the α-hemihydrate gypsum-based cementing material was 2.4 times that of the plaster-based cementing material. When the SiO₂ aerogel was added to the gypsum-based composite cementing material, the compressive strength and softening coefficient decreased with increasing SiO₂ aerogel’s content.

Aluminum oxide (Al₂O₃) powder can be added to typical cobalt-chromium (CoCr) alloy powders. In the present study, we successfully prepared alloyed samples of various powder ratios by laser cladding and analyzed their microstructure and carbide structural characteristics, including the microhardness, biological properties, morphology (using scanning electron microscopy), and crystal structure (using X-ray powder diffraction). The elemental distribution was also determined by energy-dispersive X-ray spectroscopy. The results showed that an Al₂O₃ addition caused the alloy microstructure to change from slender columnar crystals to columnar grains that were similar in shape to equiaxed grains. In addition, Al₂O₃ agglomeration zones appeared, and carbide structures were altered. The mechanism of the observed performance changes was also analyzed.

Microwave irradiation is an effective way to regenerate the activated carbon after adsorption and separation of waste. In this work, activated carbon saturated with toluene was efficiently regenerated by microwave irradiation. The maximum regeneration ratio of 77.2% was obtained under the following optimal operation conditions: saturated activated carbon of 5.01 g, microwave power of 500 W, carrier gas N₂ flow of 60 mL/min, and microwave irradiation time of 180 s. It was found that the higher microwave power may result in self-burning of activated carbon due to the presence of traces of oxygen, which might slightly deteriorate the pore structures of activated carbon. On the other hand, the lower microwave power cannot start desorption of toluene or might cause re-adsorption. The introduction of N₂ flow during regeneration was necessary to release the desorbed toluene from activated carbon, but it might cool the adsorption system under a much higher N₂ flow rate.5 page(s

In this work, 3-3 type porous lead zirconate titanate (PZT) ceramics were fabricated by incorporating particle-stabilized foams using the gel-casting method. Then, Portland cement pastes with different water/cement ratios (w/c) were cast into the porous ceramics to produce cement-based piezoelectric (PZT-PC) composites. The effects of w/c on phase structure, microscopic morphology, and electrical properties were studied. The results showed that the amount of hydrated cement products and the density of the PZT–PC composites increased with the increase of w/c from 0.3 to 0.9 and then decreased till w/c achieved a value of 1.1. Correspondingly, the values of both ε_r and d₃₃ increased with the density of the PZT–PC composites, resulting in less defects and greater poling efficiency. When w/c was maintained at 0.9, the 3-3 type cement-based piezoelectric composites presented the greatest K_t value of 40.14% and the lowest Z value of 6.98 MRayls, becoming suitable for applications in civil engineering for structural health monitoring.