Dawei Yi

Carbon dioxide emissions are the primary and most direct contributor to global warming, posing a significant hazard to both the environment and human health. In response to this challenge, there has been a growing interest in the development of effective carbon capture technologies. This study involved the synthesis of 13-X molecular sieve porous materials using solid waste coal gangue as a source of silicon and aluminum. The synthesis process involved the controlled utilization of an “alkali fusion-hydrothermal” reaction system. The resulting materials were characterized for their structure, morphology, and crystal composition using X-ray diffraction and field emission scanning electron microscopy. These 13-X molecular sieve materials were employed as adsorbents to capture carbon dioxide gas, and their adsorption performance was investigated. The findings indicated that the 13-X molecular sieve materials possess uniform pores and complete crystalline morphologies, and they exhibited an adsorption capacity of 1.82 mmol/g for carbon dioxide at 0 °C. Consequently, this study not only converted solid waste gangue into high-value products but also demonstrated effective atmospheric carbon dioxide capture, suggesting that gangue-based 13-X molecular sieves may serve as a potential candidate for carbon capture.

The microstructures and erosion–corrosion properties of boron-bearing stainless steel were researched by an erosion–corrosion tester, energy dispersive X–ray spectrometry, scanning electron microscope and X-ray diffraction analysis. The microstructures of as-cast, boron-bearing stainless steel contain M₇(B,C)₃, M₂(B,C) borocarbides and the martensite matrix; the matrix has less chromium and more nickel than those in the M₂(B,C) and M₇(B,C)₃. The microstructures in heat-treated, boron-bearing stainless steel consist of M₇(B,C)₃, M₂(B,C) and M₂₃(B,C)₆ borocarbides and ferrite, and the Rockwell hardness of heat-treated, boron-bearing stainless steel is lower than that of as-cast steel. For Cr28 white cast iron and boron-bearing stainless steel, the mixing wheel with higher rotating speed leads to a higher erosion–corrosion weight loss, and as the impingement angle increases, the erosion–corrosion weight loss increases first, and then decreases. For any erosion–corrosion experiment conditions, the erosion–corrosion resistance of boron-bearing stainless steel is better than that of Cr28 white cast iron.

The effects of thermal aging time at 400 °C on the microstructure and mechanical and corrosion behaviors of Z3CN20.09M cast stainless steel were investigated; and the corresponding thermal aging mechanism was studied. It was revealed that the changes in mechanical properties after thermal aging were mainly caused by the iron-rich phase (α) and the chromium-rich phase (α’) produced by the amplitude-modulation decomposition of ferrite. A similar trend of thermoelectric potential during thermal aging was determined in relation to the Charpy impact energy. However, the corrosion resistance of Z3CN20.09M cast stainless steel deteriorates as thermal aging time increases. When the thermal aging is longer than 3000 h, the precipitation of G phase has a great influence on the corrosion resistance. The interfacial matching relationship between G phase and the surrounding ferrite was established by selected area electron diffraction of HRTEM. The relationship is of cube-on-cube phase boundary type. The impact fracture mechanisms in relation to thermal aging time were also studied and compared.

The microstructure and erosion-corrosion performance of Fe–Cr–Ni–B alloy were studied. The experimental results were analyzed by hardness tester, energy spectrum analyzer, scanning electron microscope, X-ray diffraction analyzer. The results show that the Fe–Cr–Ni–B alloy consists of martensite and borocarbides [M₂(B, C) and M₇(B, C)₃], and M₂(B,C) and M₇(B,C)₃ borocarbides both have more chromium and less nickel than the matrix. After heat treatment, the hardness of the alloy reaches 52.3HRC. For the test alloys, the higher rotating speed test condition results in higher erosion-corrosion weight loss, and the erosion-corrosion weight loss increases first and then decreases with the increase of the impingement angle. Compared with Cr28 high chromium cast iron, in the erosion-corrosion surface of Fe–Cr–Ni–B alloy, the borocarbides are slightly broken, so, the Fe–Cr–Ni–B alloy exhibits excellent erosion-corrosion resistance under the borocarbide protection.

Purpose: The directional solidification Fe-B alloy was prepared. The microstructures and three-body abrasive wear behaviors of directional solidification alloy were investigated. Design/methodology/approach: Fe-B alloy was melted in medium frequency induction furnace. The hardness was measured on HRS-150 Rockwell-hardness tester and HXD-1000TMC tester. The wear characteristic of the alloy was examined with a block-on-ring geometry. The worn surface of the alloy was investigated by scanning electron microscopy and laser scanning microscopy. Findings: The wear weight loss and worn surface roughness increase with the increasing contact load in wear tests. When the worn surface is perpendicular to the boride growth direction, the highest hardness plane of the boride can resist abrasive effectively under the surrounding and supporting of the martensite matrix. Originality/value: The relation between boride growth direction and wear direction will cause different boride breaking tendency and wear weight loss.