Effect of Thermal-cold Cycling Treatment on Mechanical Properties and Microstructure of 6061 Aluminum Alloy

The influence of thermal-cold cycling treatment on mechanical properties and microstructure of 6061 aluminum alloy was investigated by means of tensile test, optical microscopy(OM), X-ray diffraction(XRD) and transmission electron microscopy(TEM). The cryogenic treatment mechanism of the alloys was discussed. The results show that thermal-cold cycling treatment is beneficial since it produces a large number of dislocations and accelerates the ageing process of the alloy and yields the finer dispersed β" precipitates in the matrix. This variation of microstructural changes leads to more favorable mechanical properties than the other investigated states, while grain boundary precipitation is coarse and distributed discontinuously along grain boundaries, with a lower precipitation free zone(PEZ) on the both sides of precipitated phase. As a result, the tensile strength, elongation and conductivity of 6061 aluminum alloy after thermal-cold cycling treatment are 373.37 MPa, 17.2% and 28.2 MS/m, respectively. Compared with conventional T6 temper, the mechanical properties are improved significantly.

Repair of Second-Generation Recycled Fine Aggregate of Waste Concrete from Freeze-Thaw Environment by Carbonation Treatment

The reuse of waste recycled concrete from harsh environments has become a research hotspot in the field of construction.This study investigated the repair effect of carbonation treatment on second-generation recycled fine aggregate(SRFA)obtained from recycled fine aggregate concrete(RFAC)subjected to freeze-thaw(FT)cycles.Before and after carbonation,the properties of SRFA were evaluated.Carbonated second-generation recycled fine aggregate(CSRFA)at five substitution rates(0%,25%,50%,75%,100%)to replace SRFA was used to prepare carbonated second-generation recycled fine aggregate concrete(CSRFAC).The water absorption,porosity and mechanical properties of CSRFAC were tested,and its frost-resisting durability was evaluated.The results showed after carbonation treatment,the physical properties of SRFA was improved and met the requirements of II aggregate.The micro-hardness of the interfacial transition zone and attached mortar in CSRFA was 50.5%and 31.2%higher than that in SRFA,respectively.With the increase of CSRFA replacement rate,the water absorption and porosity of CSRFAC gradually decreased,and the mechanical properties and frost resistance of CSRFAC were gradually improved.Carbonation treatment effectively repairs the damage of SRFA caused by FT cycles and improves its application potential.

Effect of Thermal Cycling Treatment on Microyield Behavior of Al_2O_3p/Al Composite

An aluminum alloy (6061) matrix composite reinforced with 35% (vol.) Al 2O 3 particles was fabricated by squeeze casting method. The Al 2O 3 particles were spherical. The microyield behavior of the composite and the effect of different thermal cycling treatment on the microyield behaviors of the composite were studied. Based on TEM and HREM observation of microstructure, the mechanism of microyield behavior in the Al 2O 3p/6061 composite was analyzed. The results indicate that the microyield behavior of the Al 2O 3p/6061 composite can be described by Brown Lukens theory, which was used satisfactorily for aluminum alloys and other light alloys, and is affected greatly by the different thermal cycling treatment. The more the cycles of thermal cycling treatment, the higher to microyield strength at small strains. Thermal cycling treatment affects mainly the thermal mismatch stress and the density of movable dislocations in the matrix.

Carbon Footprint of Recycling Service in Waste Treatment: Used Beverage Cans and Waste Papers

There are very few studies of the Carbon Footprint of Products (CFPs) in the service sector (e.g. transport and waste treatment) in comparison with those of industrial products and farm products. In this study, the CFPs of the recycling services of used beverage cans (aluminum and steel) and waste papers (cardboard, magazine and newspaper) in waste treatment were estimated as a first trial model of the service sector. Regarding the CFPs of whole life cycle of the recycling services, the amounts of CO2-equivalent (CO2e) greenhouse gas (GHG) emissions from the collection and transportation process were the largest in all recycling cases. The reason that the collection and transportation process emits the largest amounts of GHG emissions is that the collection vehicles (trucks) consume the large amounts of diesel fuel. Regarding the CFPs of the capital equipment, the amounts of GHG emissions from the capital equipment were the second largest in all recycling cases. It was found that the percentages of amounts of GHG emissions from the capital equipment in the recycling services were larger than those of industrial products and farm products.

Effects of Heat Treatment and Thermal Cycling on Martensitic Transformation Behavior of Ni_(59)Al_(11)Mn_(30) High Temperature Shape Memory Alloy

A reversible martensitic transformation (MT) takes place during cooling and heating in the solution quenched and the solution quenched plus aged Ni59AlHMn30 alloy The MT temperature increases with increasing solution temperature. The excellent MT characteristics can be obtained from a process of lOOCTC solution quenched plus 400 °C aged. Follow this process, the MT start temperature (Ms) and the reverse MT finish temperature (Af) are 469*C and 548"C, respectively. The martensitic stabilization effect in the solution quenched and aged Ni59AlnMn3o alloy is observed as an increase in the Af temperature of the first reverse MT during thermal cycles. This stabilization effect vanishes from the second thermal cycle. Thermal cycling can enhance the stability of the reversible MT. The microstructure of the quenched NisgAlnMnjo alloy consists of martensite (M) and gamma phase. The volume fraction of gamma phase is about 40%. The substructure of M and gamma phase is twins and dislocations, respectively. The hardness of M is higher than that of gamma phase. After aging treatment the basic phases of alloy do not change, but the hardness of the phases increases.

The significance of resource recycling for coking wastewater treatment:based on environmental and economic life cycle assessment

The sustainability of the coking industry is supported by reasonable production profit and environmental quality requirements.The traditional measures substantially increased the related costs for enterprises to reach standards.This paper aims to develop a comprehensive cost combined environmental impact assessment method that is necessary for the analysis of wastewater treatment systems.Typical three coking wastewater treatment processes in China were evaluated.Results showed that eutrophication dominantly contributed to the overall environmental effect.Improving effluent quality could significantly reduce the total environmental impact.In terms of an economic perspective,the price of raw materials was the main factor that affected the operating cost of comprehensive treatment.Based on subsystem analysis,the pretreatment stage accounted for the majority of environmental and cost burdens,respectively reaching 64%-78%and 64%-86%.Optimizing the pretreatment process by enhancing the efficiency of high concentration raw material recovery and substituting toxic raw materials for extractant could reduce the environmental impact and economic cost by 43.8%and 57%,respectively,which was an effective way to improve the potential performance of coking wastewater treatment plants(WWTPs).

Effect of thermal-cooling cycle treatment on thermal expansion behavior of particulate reinforced aluminum matrix composites

Two micron SiC particles with angular and spherical shape and the sub-micron Al2O3 particles with spherical shape were introduced to reinforce 6061 aluminium by squeeze casting technology. Microstructures and effect of thermal-cooling cycle treatment （TCCT） on the thermal expansion behaviors of three composites were investigated. The results show that the composites are free of porosity and SiC/Al2O3 particles are distributed uniformly. Inflections at about 300℃ are observed in coefficient of thermal expansion （CTE） versus temperature curves of two SiCp/Al composites, and this characteristic is not affected by TCCT. The TCCT has significant effect on thermal expansion behavior of SiCp/Al composites and CTE of them after 3 cycles is lower than that of 1 or 5 cycles. However, no inflection is observed in Al2O3p/Al composite, while TCCT has effect on CTE of Al2O3p/Al composite. These results should be due to different relaxation behavior of internal stress in three composites.

Life cycle assessment for waste acid treatment in zinc smelting

Lift cycle assessment(LCA)methodology was applied to evaluating and comparing two waste acid disposal processes in zinc smelting.The results indicate that environmental impacts of gas−liquid vulcanization technologies are human toxicity,abiotic depletion potential,and global warming risk,which are mainly caused in neutralizing−evaporating−crystallization unit and electrodialysis unit.As for traditional lime neutralization method,vulcanization unit is the main factor.In this regard,the total environmental impact of traditional lime neutralization method is much higher than that of gas−liquid vulcanization technologies.Furthermore,the sensitive analysis shows that electricity and sodium sulfide(60%)are sensitive factors in two waste acid disposal technologies.In addition,the total cost of disposing a functional unit waste acid in traditional lime neutralization process is nearly 27 times that of the gas−liquid vulcanization waste acid disposal technologies.

Integrated strategies for chemotherapy cycles in nasopharyngeal carcinoma patients: Real-world data from two epidemic centers guiding decision-making

objective:Two cycles of induction chemotherapy(IC)followed by 2 cycles of platinum-based concurrent chemoradiotherapy(CCRT)(2IC+2CCRT)for locoregionally advanced nasopharyngeal carcinoma(LA-NPC)is widely adopted but not evidence-confirmed.This study aimed to determine the clinical value of 2IC+2CCRT regarding efficacy,toxicity and cost-effectiveness.Methods:This real-world study from two epidemic centers used propensity score matching(PSM)and inverse probability of treatment weighting(IPTW)analyses.The enrolled patients were divided into three groups based on treatment modality:Group A(2IC+2CCRT),Group B(3IC+2CCRT or 2IC+3CCRT)and Group C(3IC+3CCRT).Long-term survival,acute toxicities and cost-effectiveness were compared among the groups.We developed a prognostic model dividing the population into high-and low-risk cohorts,and survivals including overall survival(OS),progression-free survival(PFS),distant metastasis-free survival(DMFS)and locoregional relapse-free survival(LRRFS)were compared among the three groups according to certain risk stratifications.Results:Of 4,042 patients,1,175 were enrolled,with 660,419,and 96 included in Groups A,B and C,respectively.Five-year survivals were similar among the three groups after PSM and confirmed by IPTW.Grade 3-4 neutropenia and leukocytopenia were significantly higher in Groups C and B than in Group A(52.1%vs.41.5%vs.25.2%;41.7%vs.32.7%vs.25.0%)as were grade 3-4 nausea/vomiting and oral mucositis(29.2%vs.15.0%vs.6.1%;32.3%vs.25.3%vs.18.0%).Cost-effective analysis suggested that 2IC+2CCRT was the least expensive,while the health benefits were similar to those of the other groups.Further exploration showed that 2IC+2CCRT tended to be associated with a shorter PFS in high-risk patients,while 3IC+3CCRT potentially contributed to poor PFS in low-risk individuals,mainly reflected by LRRFS.Conclusions:In LA-NPC patients,2IC+2CCRT was the optimal choice regarding efficacy,toxicity and costeffectiveness;however,2IC+2CCRT and 3IC+3CCRT probably shortened LRRFS in high-and low-risk populations,respectively.

Low cycle fatigue improvement of powder metallurgy titanium alloy through thermomechanical treatment

A low-cost β type Ti-1.5Fe-6.8Mo-4.8Al-1.2Nd (mass fraction, %)(T12LCC) alloy was produced by blended elemental powder metallurgy(P/M) method and subsequent thermomechanical treatment. Low cycle fatigue(LCF) behavior of P/M T12LCC alloy before and after thermomechanical treatment was studied. The results show that the LCF resistance of P/M titanium alloy is significantly enhanced through the thermomechanical treatment. The mechanisms for the improvement of LCF behavior are attributed to the elimination of residual pores, the microstructure refining and homogenization.

Effect of Thermal-Cold Cycle on Microstructure and Hardness of a W-Cr-Mn-Mo-V Ferro-based Hardfacing Layer

The effect of heating temperature and thermal-cold recycle times on microstructure and hardness of a W-Cr-Mn-Mo-V Ferro-based hardfacing layer was studied.The results show the surfacing layer has good high-temperature stability and ability to resist quench heat and heat softening.After thermal-cold recycle at 560°C??18°C for 120 times,the hardness of the hardfacing layer is HRC 57.5,its microstructure is mainly tempered martensite and a small amount of retained austenite,when thermal-cold recycled at 680°C??18°C for 120 times,the hardness of the hardfacing layer is HRC 44.5,martensite in the hardfacing layer has almost decomposed.

Influence of Ageing Heat Treatment on the High Cycle Fatigue of an 8090 Al-Li Alloy

Fatigue lives for the smooth and notched specimens of 8090 Al-Li alloy jn the different ageing conditions have been studied. For the smooth samples of 8090 alloy the artificial ageing results in an increase in fatigue life in comparison with natural ageing. On the contrary, the notched specimens of 8090 alloy in the naturally aged condition show higher fatigue life than in the peak-aged. The exposure to either the peak-aged or naturally aged leads to superior fatigue properties of Al-Li alloy to the traditional high strength aluminum alloys of 7075 and 2024, especially in the latter aged condition. In all ageing conditions, i,e. naturally, under-, peak- and over-aged, the peak-aged 8090 alloy displays the highest fatigue life and the over-aged material has a minimum value at the same stress amplitude. The difference in fatigue life is mainly attributable to the size and distribution of strengthening precipitates as well as the wide of precipitate free zones (PFZ's) along grain boundaries.

Effect of heat treatment on high-cycle fatigue behavior of Mg-Zn-Y-Zr alloy

High-cycle fatigue (HCF) behavior of as-forged-T5 Mg-Zn-Y-Zr wrought alloy with stress-ratio R=-1 at ambient environment was presented. The relationship between the maximum stress and the number of cycles to failure was constructed. The results show that the fatigue strength at 107 cycles of the as-forged alloy in T5 state is higher than that of the alloy in T4 state. However, in T6 state, the fatigue strength at 107 cycles is higher than those of the alloys in both T5 and T4 states.

基于“治未病”理念的中医药全周期防治高血压策略

将“治未病”理念与高血压的中医药全周期防治相结合,从“未病先防、既病防变、已变防衰”三方面强化高血压全周期干预的3级中医药防治策略,从而早期干预高血压前期、阻断高血压进展、保护靶器官,预防并发症,提高患者的生活质量,充分发挥中医药在高血压防治方面的特色和优势,为中医药在高血压防治中的应用提供理论依据。

T6态热挤压Al-5Cu-0.8Mg-0.15Zr-0.2Sc-0.5Ag合金的低周疲劳行为

为了揭示经过T6处理的热挤压Al-5Cu-0.8Mg-0.15Zr-0.2Sc-0.5Ag合金在不同温度下的低周疲劳变形与断裂行为,对T6态热挤压合金进行了室温和200℃条件下的低周疲劳实验。结果表明:在室温和200℃下合金塑性应变幅与载荷反向周次之间服从Coffin-Manson公式,而弹性应变幅与载荷反向周次之间服从Basquin公式;合金在室温和200℃下低周疲劳变形时,在较低外加总应变幅下疲劳变形机制主要为平面滑移,而在较高外加总应变幅下疲劳变形机制主要为波状滑移;室温和200℃下合金的疲劳裂纹均萌生于疲劳试样表面并以穿晶方式扩展。

CCPP机组余热锅炉高压蒸发器泄漏分析与处理

燃气-蒸汽联合循环机组(CCPP)作为高效能源转换系统,在钢铁等工业领域得到广泛应用。余热锅炉作为CCPP机组的核心部件,其稳定运行直接关系到整个机组的效率和安全性。文章针对某钢厂燃气轮机组配套余热锅炉高压蒸发器上部迎烟气面频繁泄漏问题进行了深入研究,分析泄漏原因为其下联箱内沉积物导致蒸发器管内水流量减小,进而产生汽水混合物的冲击腐蚀,同时炉膛局部区域的“烟气走廊”现象加剧了这一腐蚀过程。针对这一问题,采取更换泄漏管段、改造下联箱定排管系统以提高排污效率、修复和完善烟气挡板以减少“烟气走廊”形成、优化定期排污操作以及制定定期的检查和维护计划等措施,有效地解决了高压蒸发器的泄漏问题,提高了设备的稳定性和安全性。

低浓度稀土离子吸附材料研究进展

近年来,随着稀土产量与需求之间的供需矛盾日益加深,对稀土资源的高效绿色提取和分离提出了更高的要求.特别是从稀土矿选矿废水、精炼废水、海水和温泉等低浓度的稀土溶液中回收稀土资源已成为研究热点.相比于蒸发结晶、化学沉淀、溶剂萃取等传统提取技术,吸附法因具有操作简单、成本低廉、处理量大和适应性强等优势,成为低浓度稀土深度回收的潜在方法之一.本文汇总了近年来国内外有关于稀土离子吸附材料的研究进展,详细介绍了矿物基、碳基、金属−有机框架基和高分子基等吸附材料的设计与合成思路、微观形貌、吸附行为、材料性能和潜在的应用潜力.最后,对比指出了各种吸附材料的优势和不足,提出开发面向应用的高效绿色靶向吸附材料是未来稀土吸附材料的主要发展趋势,靶向吸附技术也将成为低浓度稀土溶液(废水)资源化的主要方法,以期为稀土资源的高效利用提供参考.

深冷循环热处理下锆基金属玻璃的回春行为调控

研究Zr_(55)Cu_(30)Ni_(5)Al_(10)(摩尔分数,%)金属玻璃在深冷循环处理过程中的回春行为。实验发现,随着循环次数的增加,样品的回春程度更高,表现为更高的弛豫焓与更低的密度。回春程度经200次循环后逐渐饱和,这可能与非晶结构中有限的自由体积含量有关。同时,高循环次数下的样品硬度更低,塑性更好,这与其剪切转变区体积增大有关。此时,更低的剪切面形成能有利于多重剪切带的形成。此外,还发现自由体积含量与样品塑性应变及剪切转变区体积呈线性关系。分子动力学模拟结果还表明,在高冷速下回春程度高的样品会发生原子体积的饱和。

电化学治疗对宫颈癌细胞系细胞周期及CDK、cyclin表达的影响

目的:探讨不同电化学治疗剂量对肿瘤细胞生长周期的影响、细胞周期变化特点及对宫颈癌细胞系CDK和cyclin表达的影响。方法:用体外实验方法,用不同电化学剂量处理宫颈癌细胞系后分别用流式细胞仪和RT-PCR测定细胞周期分布及细胞CDK和cyclin mRNA的表达。结果:(1)不同电化学治疗剂量组合作用后S期细胞所占比例均低于空白组,差异有统计学意义(P<0.01),但G1细胞所占比例均高于空白组,差异有统计学意义(P<0.01)。G2期细胞所占比例与空白对照的差异无统计学意义(P>0.05);(2)(5V,10C)、(10V,10C)处理组cyclin D1表达阴性;(5V,5C)、(10V,5C)处理组cyclinD1表达阳性。各电化学剂量处理组CDK4、CDK1、cyclin B1表达均阳性;(3)不同电化学治疗剂量组合作用后各基因表达与G2期比例无明显相关,但cyclinD1基因表达与G1期呈负相关,与S期呈正相关。CDK1基因表达与G1期呈正相关,与S期呈负相关。结论:电化学治疗能通过调节肿瘤细胞CDK和cyclin基因的表达影响其细胞周期各时相的分布。

湖北省典型农村生活污水处理技术比选

农村生活污水治理是攻坚战的一项重要任务。由于湖北省地形复杂、河流众多、农村人口居住分散,农村污水治理存在很多困难和问题,亟需探索适合的实用处理工艺和技术模式。该文利用SimaPro 9.0软件,对湖北省4种典型农村生活污水处理技术——人工湿地、厌氧-好氧工艺、膜生物反应器和生物接触氧化法(BCO)建立生命周期评价模型,对比各系统全生命周期内的环境影响,并结合成本分析为农村生活污水处理技术的择选提供决策依据。结果表明:呼吸无机物是最主要的环境影响类型,与原材料生产、运输过程涉及大量化石能源的使用有关;各系统的环境影响主要来自建设阶段(99%),经济成本主要来自运行阶段(80%);BCO是4种典型技术中低环境影响、低成本的最佳方案。基于评价结果,可通过清洁生产、降低能耗等措施改善处理技术对环境和经济的负面影响,促进农村水环境的可持续发展。