热轧双相钢生产现状、存在问题及发展趋势浅析

介绍了国内外热轧双相钢的发展现状；对热轧双相钢的成分体系和关键生产工艺进行了总结，指出了目前热轧双相钢在生产过程中存在的问题；提出了未来热轧双相钢的主要发展方向为低成本、高强度、低负荷、高表面质量和“以热代冷”。     

D-limonene Inhibits Pentylenetetrazole-Induced Seizure via Adenosine A2A Receptor Modulation on GABAergic Neuronal Activity

Background: Epilepsy is a chronic neurological disorder characterized by the recurrence of seizures. One-third of patients with epilepsy may not respond to antiseizure drugs. Purpose: We aimed to examine whether D-limonene, a cyclic monoterpene, exhibited any antiseizure activity in the pentylenetetrazole (PTZ)-induced kindling mouse model and in vitro. Methods: PTZ kindling mouse model was established by administering PTZ (30 mg/kg) intraperitoneally to mice once every 48 h. We performed immunoblot blots, immunohistochemistry (IHC), and high-performance liquid chromatography (HPLC) analysis after the behavioral study. Results: An acute injection of PTZ (60 mg/kg) induced seizure in mice, while pretreatment with D-limonene inhibited PTZ-induced seizure. Repeated administration of PTZ (30 mg/kg) increased the seizure score gradually in mice, which was reduced in D-limonene (10 mg/kg)-pretreated group. In addition, D-limonene treatment increased glutamate decarboxylase-67 (GAD-67) expression in the hippocampus. Axonal sprouting of hippocampal neurons after kindling was inhibited by D-limonene pretreatment. Moreover, D-limonene reduced the expression levels of Neuronal PAS Domain Protein 4 (Npas4)-induced by PTZ. Furthermore, the adenosine A2A antagonist {"type":"entrez-protein","attrs":{"text":"SCH58261","term_id":"1052882304","term_text":"SCH58261"}}SCH58261 and ZM241385 inhibited anticonvulsant activity and gamma-aminobutyric acid (GABA)ergic neurotransmission-induced by D-limonene. Conclusion: These results suggest that D-limonene exhibits anticonvulsant activity through modulation of adenosine A2A receptors on GABAergic neuronal function.     

粉末注射成型技术的研究和应用

介绍了粉末注射成型技术的概念和工艺,包括金属粉末注射成型(MIM)、陶瓷粉末注射成型(CIM),讲述了黏结剂的使用发展情况;阐述了粉末注射成型专用注射成型机的特点,PIM粉末注射专用塑化系统,PIM专用料斗滑块装置,镶套式机筒座等,介绍了PIM技术在诸多行业中的应用,3C行业,医疗行业,汽车行业等,并展望了PIM研究的发展方向。     

铝碳质长水口用低铝抗氧化涂层的研制

为抑制铝碳质长水口使用过程中石墨的氧化，其表面会涂覆含 20%~30%Al₂O₃的抗氧化涂层，但切割丝钢等特种钢冶炼过程必须严格控制钢液中夹杂的 Al₂O₃的含量，因此需要制备低氧化铝含量的抗氧化涂层。本文通过调节涂料组成、加水量和水玻璃加入量制备了低铝抗氧化涂层，并利用扫描电镜分析了抗氧化实验后试样断口的显微结构。结果表明：以粘土粉、钾长石粉和硅砂为主要原料，添加 10%硼砂的涂料可在 800 ℃形成良好的釉层，此时涂料中 A12O3的含量可降至 12%，得到了低铝涂料；当加入占涂料质量 80%的水和 40%的水玻璃时，涂层具有最佳的涂覆性能和抗氧化性能，涂层和长水口基体结合致密，保护了长水口中的石墨不被氧化。     

Quantitative analysis of toughening effect of crack deflection on Si3N4/Si2N2O composites through improved indentation method

In this study, Si₃N₄/Si₂N₂O composite ceramics prepared by hot pressing were used as an example, and the material fracture morphology and fracture mechanism were analyzed. Based on the formula of fracture toughness measured by an indentation method, a quantitative computation method was proposed to determine the toughened effect of ceramic materials resulting from the crack deflection by the second phase. The grain size and sintering density are increased with the increase of sintering temperature. The toughening effects resulting from the crack deflection is increased, and the main mode of fracture is transformed into the transgranular fracture. The Si₂N₂O grains can play a role in the toughening process because these grains can hinder the cracks extending along the radial direction. However, when the cracks extend in the axial direction, the toughening effect of Si₂N₂O grains is not obvious because of the internal stacking faults in the axial direction. The improved indentation method can quantitatively analyze the toughening effect of the second phase of composite ceramics, and the validity of this method are verified by comparing the fracture toughness of Si₃N4/Si₂N₂O and fine grained β- Si₃N₄ ceramics.     

Influence of pore distribution on the equivalent thermal conductivity of low porosity ceramic closed-cell foams

The microstructures of porous alumina materials with different porosities were established by introducing the departure factor of pore position and acentric factor of pore diameter to describe the distribution of pores in space and in size, respectively. The contribution of radiation and influence of pore distribution on the equivalent thermal conductivity were discussed based on numerical simulations by the finite volume method (FVM) considering both thermal conduction and radiation. When the pore diameter was less than 10?µm, the radiation component was less than 2%, and radiation could be neglected. Radiative heat transfer played a dominant role for materials with high porosity and large pore size at high temperatures. For micro pore materials (<?100?µm), broad pore size and non-uniform pore space distribution decreased the thermal conductivity across the entire temperature range. For materials with macro pores (>1?mm), broad pore distribution decreased the thermal conductivity at low temperatures and increased it at high temperatures. The basic prediction model of effective thermal conductivity for a two-component material, the Maxwell–Eucken model (ME1) and its modified model were corrected by introducing the pore structure factor. The results from experiments prove that the numerical values were satisfactory.     

New anti-ablation candidate for carbon/carbon composites: Preparation,composition and ablation behavior of Y2Hf2O7 coating under an oxyacetylene torch

Y₂Hf₂O₇ possesses low thermal conductivity and high melting point, which make it promising for a new anti-ablation material. For evaluating the thermal stability and the potential applications of Y₂Hf₂O₇ on anti-ablation protection of C/C composites, Y₂Hf₂O₇ ceramic powder was synthesized by solution combustion method and Y₂Hf₂O₇ coating was prepared on the surface of SiC coated C/C composites using SAPS. Results shown that the coating exhibits good ablation resistance under the heat flux of 2.4?MW/m² with the linear and mass ablation rates are 0.16?μm?s^?1 and ?0.028?mg?s^?1, respectively, after ablation for 40?s. With the prolonging of the ablation time, the increasing thermal stress causes the increase of cracks. Moreover, the chemical erosion from SiO₂ and the physical volatilization of low temperature molten products aggravate failure of the Y₂Hf₂O₇ coating.     

Effect of sintering aids on the densification and electrical properties of SiO2 –containing Ce0.8Sm0.2O1.9 ceramic

In this work, five different metal-oxide additives (metal?=?Ba, Co, Fe, Li, and Mn) were examined as sintering aids and SiO₂ impurity scavengers for Ce_0.8Sm_0.2O_1.9 (SDC). 2?mol% additives were loaded into the SDC with ～150?ppm (moderately impure) and ～2000?ppm (highly impure) SiO₂. Ba-, Co-, Fe- and Mn-oxides showed comparative sintering-aid effect on both moderately- and highly-impure SDC specimens, but the sintering-assisting effect of Li-oxide was completely neutralized in highly impure SDC. Regarding electrical property, the deleterious effect of 2000?ppm SiO₂ impurity on the grain-boundary conduction of SDC can be effectively alleviated by adding Ba-, Co-, Fe-, or Mn-oxides. Microstructure analysis revealed that Ba-oxide reacted directly with SiO₂ and consequently enhanced grain-boundary conduction. By contrast, with the addition of Co-, Fe-, and Mn-oxides, the improved grain-boundary conductions of impure SDC were related to the scavenging reactions between Si, Ca (another original impurity) and Sm components.     

High‐performance thermosets with tailored properties derived from methacrylated eugenol and epoxy‐based vinyl ester

A renewable chemical, eugenol, is methacrylated to produce methacrylated eugenol (ME) employing the Steglich esterification reaction without any solvent. The resulting ME is used as a low‐viscosity co‐monomer to replace styrene in a commercial epoxy‐based vinyl ester resin (VE). The volatility and viscosity of ME and styrene are compared. The effect of ME loading and temperature on the viscosity of the VE–ME resin is investigated. Moreover, the thermomechanical properties, curing extent and thermal stability of the fully cured VE–ME thermosets are systematically examined. The results indicate that ME is a monomer with low volatility and low viscosity, and therefore the incorporation of ME monomer in VE resins allows significant reduction of viscosity. Moreover, the viscosity of the VE–ME resin can be tailored by adjusting the ME loadings and processing temperature to meet commercial liquid molding technology requirements. The glass transition temperatures of VE–ME thermosets range from 139 to 199 °C. In addition, more than 95% of the monomer is incorporated and fixed in the crosslinked network structure of VE–ME thermosets. Overall, the developed ME monomer exhibits promising potential for replacing styrene as an effective low‐viscosity co‐monomer. The VE–ME resins show great advantages for use in polymer matrices for high‐performance fiber‐reinforced composites. This work is of great significance to the vinyl ester industry by providing detailed experimental support. © 2018 Society of Chemical Industry