Standoff Detection of Oil and Powder Mixtures at 12 Meters Using a Tunable Quantum Cascade Laser-Based System with a Close Focus Telescope and Uncooled Infrared Detector

We have designed and demonstrated a quantum cascade laser (QCL) based standoff system that utilizes an uncooled mercury cadmium telluride (MCT) detector with lock-in signal processing for chemical identification at a distance of 12.5 meters in indoor ambient light conditions. In the system, a tunable quad-QCL operating (1 MHz) in quasi-continuous wave mode between 8.45 and 10.03 μm (∼1182 to 1000 cm−1) serves as the active mid-infrared source for remotely interrogating mineral, powder, and thin film oil samples including powder mixtures (6, 12.5, 25, and 50%) of crystalline quartz (SiO2) in KBr. Light as reflected from a given sample is collected using a 10-inch (25.4 cm) Dall Kirkham telescope and coupled with ZnSe optics to an uncooled MCT detector. The mixture dependence of the highly transparent KBr and strongly absorbing quartz was found to fit a modified version of the Schatz reflectance model for compacted powder mixtures. All reflectance spectra reported are relative to an Au-coated diffuse reflector. A NIST traceable polystyrene standard reflector was also used to determine the QCL wavelength tuning range and calibration.

Strength properties of biopolymer treated clay/marble powder mixtures

Depending on their unique layer structures and chemical structures, soil problems such as swelling, settlement and loss of strength can be seen especially on clay soils when exposed to water. Settlement occurring on clay soils on which the structure is built, causes various damages in the building. Additionally, in the clay soil interacting with water, strength loss occurs due to the effect of the building load. Today, when soil improvement techniques are developed and diversified, clay soils can be stabilized by using different additives. A clay soil that has been improved by adding waste marble powder within the scope of this study in certain percentages (5%, 15%, 25%), biopolymer added clay / marble powder samples were obtained by interacting with locust bean gum in certain percentages (0.5%, 1%, 1.5%). There are many studies in the literature on improving clay soils using only marble powder or only biopolymer. In this study, marble powder and biopolymer were used together and thus, the feasibility of a more effective soil improvement has been investigated. The results showed that the unconfined compressive strength of the biopolymer added clay-marble powder mixtures are higher when compared with natural clay. Similarly, shear box test results showed that the unconsolidated-undrained cohesions and internal friction angles of the doped clay samples increased. It was observed that the strength values of marble powder-added clay increased after improving with biopolymer.

Effect of the Hot Deformation Conditions on Structure and Mechanical Properties of AlCr/AlCrSi Powder Composites

Aluminum matrix composites usually contain strengthening particles of refractory compounds (SiC, Al2O3) that do not react with the Al matrix. There is a problem in producing the Al matrix composite with inclusion of metals that can generate intermetallic compounds with aluminum. In this case, a conventional sintering of powder mixtures results in high porosity due to volume growth. That is why some new methods of producing dense Al matrix composites are required. A possibility to create a dense powder Al-based composite containing hard components, such as chromium and silicon, without using the sintering process, is considered. This paper presents study results of structural and mechanical properties of Al-Cr and Al-Cr-Si composites produced by hot compaction of powder mixtures. An analysis of the relationship between mechanical properties and structures of Al-Cr and Al-Cr-Si composites is carried out. Optimal values for thermomechanical processing modes that ensure sufficient strength and plasticity are determined. It is shown that strong bonding of the aluminum particles occurs under hot deformation, and an aluminum matrix is formed that provides acceptable composite bending strength as a result. The presence of chromium and silicon hard inclusions is not a significant obstacle for aluminum plastic flow. Al-Cr and Al-Cr-Si composites produced by hot deformation of the powder mixtures can be used as cathode material for the deposition of wear-resistant nitride coatings on metalworking tools.

Investigation of MXenes Oxidation Process during SPS Method Annealing

This paper discusses the effects of the environment and temperature of the Ti3C2 (MXene) oxidation process. The MXene powders were annealed at temperatures of 1000, 1200, 1400, 1600, and 1800 °C in argon and vacuum using a Spark Plasma Sintering (SPS) furnace. The purpose of the applied annealing method was to determine the influence of a high heating rate on the MXene degradation scheme. Additionally, to determine the thermal stability of MXene during the sintering of SiC matrix composites, SiC–C–B–Ti3C2 powder mixtures were also annealed. The process parameters were as follows: Temperatures of 1400 and 1600 °C, and pressure of 30 MPa in a vacuum. Observations of the microstructure showed that, due to annealing of the SiC–C–B–Ti3C2 powder mixtures, porous particles are formed consisting of TiC, Ti3C2sym, and amorphous carbon. The formation of porous particles is a transitional stage in the formation of disordered carbon structures.