Materials Letters: X最新文献

In the present paper, we reported the sensing behavior and mechanism of a titanium dioxide-based thick film sensor for the detection of propanol at room temperature. Undoped titanium dioxide (UTO) and 2 wt% cadmium sulfide doped titanium dioxide (CdTO) thick film samples are fabricated on an alumina substrate. The response of the fabricated samples is measured with varying concentrations of propanol (0–5000 ppm) in a testing chamber at room temperature. The measurement showed that the 2 wt% CdS doped sample showed a maximum response (63 %) for propanol. The transient response is also measured and the response time is 65 s and recovery 195 s.

Various rod-shape SnO₂ nanocrystals of different sizes and shapes were synthesized to study the desirable morphology for photocatalytic applications. An optimal apparent photocatalytic rate constant of 0.0809/min⁻¹ was achieved for smaller SnO₂ nanorods with diameter of ∼2.9 nm and with length of ∼9.3 nm, which is attributed to suitable nanostructures and high crystallinity. Photocatalytic activities as a function of growth and evolution of SnO₂ nanorods are revealed.

Herein, characteristics of the nanostructured silica powders (NsSP) synthesized from Philippine rice hull ash-based sodium silicate solution by precipitation (pH 2, pH 6) and calcination (600 °C, 900 °C) were presented. Characterizations confirmed that the synthesized NsSP contains high amount of SiO₂. NsSP obtained at pH 2 revealed higher mass losses by ∼ 12 % until 900 °C and higher intensities of –OH and Si–OH bonds than obtained at pH 6. Calcination of NsSP at 900 °C removes the Si–OH bond leading to a relative growth in the SiO₂ primary particles but SiO₂ structure remained amorphous. Morphology of NsSP obtained at pH 2 were cloud-like while NsSP obtained at pH 6 were bead-like and more distinct.

Composite polyurethane (PU) foams were effectively synthesized by the mass polymerization method with concentrations of natural basalt powder from 0 to 100 wt%. By increasing basalt's content, the foams had more considerable growth, suggesting a catalyst effect of its inherent metallic compounds during the reaction. Adding basalt powder decreased the traction and compression resistances and increased the foam's density and thermal stability. Still, the increase in basalt content reduced the burning time of the foams, indicating enhanced properties as a flame retardant and self-extinguishing capacity compared to traditional foams.

In the present work, we report the fabrication and characterization of undoped ZnO and Cadmium Sulfide (CdS) and Zinc Oxide (ZnO) thick films. The structural properties of ZnO films are characterized by X-ray Diffraction (XRD). It is evident from XRD that, the crystallite size of fabricated ZnO and CdS-ZnO films are 45 nm and 38 nm respectively. Optical properties have been investigated by U-V absorption. It is observed from U-V Spectroscopy that the band gap decreases with CdS doping. We found that all deposited ZnO thin films are to be polycrystalline structures of wurtzite, and the crystallite size of ZnO is in the nanometric range which further decreases with CdS doping.

Rational method for micro alloying auto sheet rolled steel of low-pearlite, 10 HFTBch steel, which contributed to more uniform indicators of the mechanical properties of welded joints obtaining in the heat-affected zone and weld was chosen. It brought them closer to the properties of the base metal.

The solidification rate of materials affects the properties of the cast product and the pouring temperature also influences the freezing conditions of cast-metal alloys. The propose of this study is to evaluate the tensile strength of cast samples by using five variations of pouring temperatures through permanent molds by a gravity casting process. The results showed that the tensile strength maximum was 443 MPa at 1210 °C, the freezing range affected the tensile properties of cast samples.

The use of engineering ceramics with intricate geometries is limited by manufacturing processes and lack ease of machinability of ceramics. Additive manufacturing of pre-ceramic polymers which are pyrolyzed into ceramics after 3D printing has recently been used to circumvent traditional manufacturing processes creating ceramics with complex geometries, however, mechanical characterization is limited. Polymer-derived ceramics and their green-body precursors are printed using digital light projection 3D printing in two orientations (0°- and 90°- to the build plate) and mechanically characterized. The results show that mechanical anisotropy exists both in the green-body polymer samples where the 0°-samples are stronger and stiffer than their 90°-counterparts and the final ceramics, where the stronger samples are fabricated at 90° despite isotropic hardness measurements. Through the manufacturing process, it was noted that samples undergoing pyrolysis built in the 90°-orientation have a pyrolysis survival rate of 94% whereas the 0°-samples showed a survival rate of 54%. The results suggest that the build-direction of 3D printed green-bodies plays a role in both material manufacturing and mechanical integrity of the final ceramic materials.

Laser powder bed fusion (LPBF) has revolutionized many industries. In this paper, we report a new approach of LPBF for oxide ceramics with selective oxidation that reduces cracks and manufacturing defects. In this method, laser energy density was used to control the oxidation within the material article. Cuprous oxide was additively manufactured into CuO with remarkable crack reduction and improvement in microstructure. The effect of process parameters on the microstructure of Cu₂O and its oxidation behavior toward energy beam of different laser powers were analyzed. The experimental results clarified that the oxidation was increased by increasing the laser power in the presence of oxygen.