Papers by Keyword: Preparation Process

Abstract: With the aim of developing an active catalyst for a direct methanol fuel cell and its preparation process, PtRu supported on reduced graphene oxide (RGO), PtRu/RGO, was prepared by three different processes using RGO with different sizes, i.e., large and small. The first process (A) involves the drying of RGO, the second one (B) does not involve the drying, and the third one (P) also does goes not involve the drying but goes through a polydopamine modification. (A) results in large agglomerates of RGO due to stacking and PtRu also formed agglomerates of nanoparticles on the outer surface of the RGO agglomerates. (B) resulted in a low Pt utilization due to the stacking of RGO. (P) improved its ECSA, Pt utilization and mass activity due to the modification that allows a homogeneous and small size PtRu deposition on the RGO. However, a problem with the modification that reduce the positive interaction between PtRu and RGO was also suggested. A smaller RGO was preferred in (P), but not in (A) and (B).

Abstract: Nanocopper has become one of the research hotspots of metal powder for 3D printing, due to its excellent properties. In this paper, technical methods, process flow and research progress were systematically introduced of nanocopper powder for 3D printing. Preparation of nano-copper powder for 3D printing are mainly physical and chemical methods. Physical methods include atomization method, physical vapor deposition method, grinding method, electric explosion method. Chemical methods include sol-gel method, radiation chemistry, plasma, microemulsion, hydrothermal, liquid reduction and so on. The advantages and disadvantages of these methods were compared in detail, and the future development direction of nano-copper powder for 3D printing was look forward to.

Abstract: Continuous through-porous pure aluminum flat pipes were prepared continuously by a self-developed depoling continuous casting technology. An online measurement and control of mold temperature at free end of graphite core rods was realized, which was critical for the preparation. The quality of flat pipes was characterized. The results show that the flat pipes could be successfully prepared with the following process parameters: melt with temperature of 750 °C, cooling water with temperature of 20 °C and flow volume of 400 L·h^-1, heat insulating mattress with thickness of 2 mm, mold temperature ranged from 635°C to 655°C and continuous casting speed ranged from 1 mm∙min^-1 to 4 mm∙min^-1. The flat pipe had cross-section dimensions of 14 mm×5 mm, which was aligned unidirectional pore diameter of 3 mm, pore number of 3 and smooth internal and external surface. The pore surfaces of flat pipes became smoother with the reduction of the graphite core rod surface roughness. When the surface roughness of graphite core rods was 0.531 μm and 0.124 μm, the corresponding surface roughness of pores was 0.581 μm and 0.184 μm, respectively. The mold temperature at the free end of graphite core rods was kept at a low thermal temperature range which was 5~25 °C lower than the solidification point of pure aluminum that is necessary for stable depoling continuous casting.

Abstract: The glass membrane was fabricated by non-solvent-induced phase separation (NIPS) and sintering technique. The preparation process was studied. PVDF was dissolved into DMAc completed. Subsequently, the used glass powder was added into above aqueous solution. The obtained slurry was tape-casted and a green membrane formed. The green membrane was immersed into coagulation bath. The exchange between DMAc and water in coagulation bath took place, and PVDF-containing glass membrane was obtained. The membrane was calcined at different temperature, and the glass membrane was prepared. In order to evaluate the porosity of membrane, many factors including water content in coagulation bath, PVDF content in slurry, coagulation bath temperature and calcination temperature were studied. The viscosity of slurry and shrinkage of membrane after calcination were also studied.

Abstract: In this paper, a series of xLiFePO₄·yLi₃V₂(PO₄)₃/C (x/y = 1:0, 7:1, 5:1, 3:1, 1:1, 1:3 and 0:1, ratio in mol) nano-sized composite cathode materials were successfully prepared via the solid reaction method. Influence of x/y ratio, calcination temperatures and the content of citric acid on the composition, microstructure and electrochemical properties of the materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical measurements, et al. results showed that the xLFP·yLVP/C (x and y ≠ 0) composites were composed of olivine LiFePO₄ and monoclinic Li₃V₂(PO₄)₃, both of which featured slight structural distortions as the formation of V-doped LFP/C and Fe-doped LVP/C, respectively; With the increase of calcination temperatures, the crystallinity and particles size of the 7LFP·LVP/C composites increased, when calcined at 700°C, the initial charge/discharge specific capacity of the composites reached a maximum value of 145.6 mAh/g, and the voltage drop values between charge/discharge platform possessed the minimum value(0.04 V), suggesting the minimum polarization of the composites in charge/discharge process. Content of citric acid did not affect the compositions of the composites, with the increase of the molar ratio of citric acid to V³⁺, the discharge specific capacities of 7LFP·LVP/C increased first and then decreased, when it equaled to 1.0:1.0, the discharge specific capacity of the relative composites was 119.18 mAh/g, with a capacity retention rate of 93.9 % after 50 cycles, owning the excellent electrochemical stability.

Abstract: In this work, the influences of process parameters including electroplating time, annealing temperature, etchant concentration and dealloying time on the microstructures of nanoporous copper (NPC) were quantitatively evaluated in terms of pore size. Taguchi method was utilized to reduce the number of experiments required for the evaluation. The effect of each parameter variable on the characterization length scale of NPC was quantified and discussed. It was found that the annealing temperature was the most dominant factor influencing the microstructure of NPC and the dealloying time, electroplating time and etchant concentration contributed sequentially weakly to that of NPC.

Abstract: Heat vulcanized silicon rubber was prepared by mixing technology. The influences of factors on silicon rubber performance were investigated such as raw rubber dosage, thermal-resistant additive dosage and process conditions. The results show that the optimal formula is as follows: 28.8phr raw rubber containing 0.23 vinyl group, 0.4phr white carbon black dispersant, 10phr vapor white carbon black, 0.5phr iron oxide, 0.7phr zinc oxide, 0.99phr thermal-resistant additive, 0.4phr accelerator DM and 0.6phr benzoyl peroxide. After placed for 24h, the mixture underwent two-step vulcanization (127°C×10.0MPa×6min and 200°C×4h). The thermal-resistant performance of silicon rubber was dramatically improved by thermal-resistant additive.

Abstract: In Xinjiang, by making use of cotton stalks after cotton picked, people researched and developed a kind of walling material that is cotton stalks cement-based blocks, elaborated its preparation methods, and evaluated its technology effect of cotton stalks cement-based block material. Results show that the cotton stalks cement-based block material have good properties like wide source, easy processing and wonderful performance; by soaking cotton straw broken material with alkali liquor, made cotton straw plant fiber reinforced material and the cement matrix have good interface adhesion; the block material is provided with load-bearing, heat preservation performance and cracking resistance, it can be used for low-rise buildings bearing wallboard and retaining wall of multiple floors in cotton planting region.

Abstract: Piezoelectric material which can be used as both sensor and drive is an important kind of smart material. Studies on piezoelectric materials are now the research focus and hotspots of smart materials which have achieved fruitful results. This article describes the working principle of smart piezoelectric materials, provides an overview of the preparation progresses and application status, based on which the research and development trends are discussed.

Abstract: Due to the excellent physical and chemical characteristics and mechanical properties of the tungsten heavy alloy (WHA), the WHAs have been widely applied in many areas of the national economy. In this paper, the concept of the WHA is introduced briefly, and the preparation process and properties of the WHAs are summarized. Compared with depleted uranium alloy, the WHA shows broad application prospects in the field of kinetic energy projectile.