Microstructure evolution and thermal expansion of Cu-Zn alloy after high pressure heat treatment

The thermal expansion coefficients of Cu-Zn alloy before and after high pressure treatment were measured by thermal expansion instrument in the temperature range of 25？700 ℃,and the microstructure and phase transformation of the alloy were examined by optical microscope,X-ray diffractometer（XRD） and differential scanning calorimeter（DSC）.Based on the experimental results,the effects of high pressure treatment on the microstructure and thermal expansion of Cu-Zn alloy were investigated.The results show that the high pressure treatment can refine the grain and increase the thermal expansion coefficient of the Cu-Zn alloy,resulting in that the thermal expansion coefficient exhibits a high peak value on the α-T curve,and the peak value decreases with increasing the pressure.

Heat treatment and granule medium internal highpressure forming of AA6061 tube

The new forming process of AA6061 alloy tube, including solution treatment, granule medium internal high-pressure forming and aging treatment, was developed. The AA6061 alloy tube via heat treatment satisfied the forming requirement, and the granule medium internal high pressure forming method for AA6061 alloy tube was also realized by using convenient implementation with low requirement of equipment and flexible design of product. At a solution temperature of 560℃ and time of 120 min, the elongation of the AA6061 extruded tube increases by 300% and the strength and the hardness dramatically decrease too. Therefore, the AA6061 alloy tube meets the requirement of internal high-pressure forming because of the improvement of formability. The experiments shows that the strength and hardness of AA6061 alloy workpiece recover to that of the as-received alloy at an aging temperature of 180℃ and time of 360 min, and the strength of AA6061 alloy workpiece is equal to the base alloy. The typical parts of convex ring tube, stepped shaft tube and hexagonal tube were successfully produced in lab by using the present forming method. The forming tests show that the maximum expansion ratio(MER) of the AA6061 extruded tube increases by 25.5% and the material properties of formed AA6061 alloy tube reached the performance of as-received alloy.

INFLUENCE OF HEAT TREATMENT ON OXIDATION PROPERTIES OF C/C COMPOSITES FABRICATED BY HIGH PRESSURE IMPREGNATION CARBONIZATION

Felt base carbon/carbon composites fabricated by super-high pressure impregnation carbonization process (SPIC) were heat treated at high temperature 2773K. The oxidation properties of felt base carbon/carbon composites were investigated at different temperatures (773-1173K), and the microstructures of carbon/carbon composites were studied by SEM and X-ray diffraction. The experimental results showed that the inter-laminar distance of (002) plane (d002) deceased while the microcrystalline stack height (Lc) increased. The oxidation rate of felt base carbon/carbon composites was invari-able at certain temperatures. The oxidation mechanism of carbon/carbon composites changed remarkably at the oxidation temperature 973K. At the initial oxidation stage of carbon/carbon composites, carbon matrix was oxidized much more rapidly than carbon felt.

Effect of High Pressure Heat Treatment on Microstructure and Compressive Properties of Low Carbon Steel

The effect of high pressure heat treatment on microstructure and compressive properties of low carbon steel were investigated by optical microscope,transmission electron microscope,hardness tester and compression test methods.The results show that martensite appears in low carbon steel at 1-5GPa GPa and 950°C for 15 minutes treatment,high pressure heat treatment can improve the hardness and compressive properties of the steel,the yield strength of the steel increases with increasing pressure,and its compressive properties are better than that treated under normal pressure quenching.

Effects of high-pressure heat treatment on the solid-state phase transformation and microstructures of Cu_(61.13)Zn_(33.94)Al_(4.93) alloys

The phase transformation activation energy of the Cu61.13Zn33.94A14.93 alloys, which were treated at 4 GPa and 700 ℃ for 15 minutes, was calculated by means of differential scanning calorimetry curves obtained at various heating and cooling rates. Then, the effects of high-pressure heat treatments on the solid-state phase transformation and the microstructures of Cu61.13Zn33.94A14.93 alloys were investigated. The results show that high-pressure heat treatments can refine the grains and can change the preferred orientation from （111） to （200） of α phase. Compared with the as-cast alloy, the sample with high-pressure heat treatment has finer grains, lower β＇→β and/β→β＇ transformation temperature and activation energy. Furthermore, we found that high cooling rate favours the formation of fine needle-like α phase in the range of 5-20℃/min.

Flexible Furnace Concepts for Vacuum Heat Treatment Combined with High-pressure Gas Quenching

IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.

High Pressure Water-Jet Technology for the Surface Treatment of Al-Si Alloys and Repercussion on Tribological Properties

Recent developments in high pressure water-jet technology have brought the process to the forefront as a means of surface treatment. Water jet technology offers cleaning, cutting, processing as well as potential refinement of surface properties. By adapting the process parameters the surface characteristics can be changed while the profile remains the same. In the present study, water-jet technology was used for the surface treatment of Al-Si alloy to investigate its effect on tribological properties. Dry sliding wear behavior was investigated against AISI 52100 bearing steel ball using a reciprocating ball-on-flat configuration. Optical microscopy examination reveals that ploughing of grains, transgranular and intergranular propagation of cracks;are the mechanisms by which material is removed during water jet treatment. While, on the other hand, SEM observation of the wear track reveals that plastic deformation and delamination are the dominant wear mechanism during the wear process. Water jet treatment was compared to hot isostatic pressing in terms of its effects on wear resistance and surface porosity of Al-Si alloy. It was found that, hot isostatic pressing reduces the total amount of porosity at the expanse of hardness while water jet treatment produces a compressed surface having higher hardness and compressive residual stress, which ultimately increases wear resistance.

Train of Thought about Treatment of High Blood Pressure with Integrative Traditional and Western Medicine

Based on the differ—ent theories,TCM andWestern medicine(WM)have their owndifferent understandingsabout the pathogenesisand treatment of highblood pressure(HBP).In TCM the balancesbetween blood-qi,vis—cera—bowel, and yin—yang are all highly

Nursing Effects of Medical Treatment Combination on Patients at High Risk of Developing Pressure Ulcers at Rural Homes

Objective:To explore the nursing effects of medical treatment combination on patients at high risk of developing pressure ulcers at rural homes.Methods:From January 2018 to December 2018,86 patients at high risk of developing pressure ulcers at rural homes who were in Wenjiang Hospital were randomly divided into a control group and an observed group.The control group received the routine publicity and education and visiting,while the observed group adopted the cooperative nursing model of medical treatment combination.Then compare the healing status and nursing satisfaction of the two groups.Results:Of the 43 patients with pressure ulcers in the observed group,18 had been in the second stage of pressure ulcers and 16 had been healed;14 had been in the third stage of pressure ulcers and 8 had been healed;11 had been in the fourth stage of pressure ulcers and 5 had been healed.The nursing satisfaction of the patients in the observed group was 95.35%.Conclusion:Conducting medical treatment combination on patients at high risk of developing pressure ulcers at rural homes can effectively improve the patients’and their families’awareness of pressure ulcer nursing,standardize their nursing behaviour,help recover the patients themselves and promote the patients’satisfaction.

Formability and strengthening mechanism of AA6061 tubular components under solid granule medium internal high pressure forming

A new technological process of tube forming was developed, namely solution treatment → granule medium internal high pressure forming → artificial aging. During this process, the mechanical properties of AA6061 tube can be adjusted by heat treatment to satisfy the process requirements and the processing method can also be realized by granule medium internal high pressure forming technology with the features of convenient implementation, low requirement to equipment and flexible design in product. Results show that, at a solution temperature of 560 ℃ and time of 120 min, the elongation of AA6061 increases by 313%, but the strength and the hardness dramatically decrease. At an aging temperature of 180 ℃ and time of 360 min, the strength and hardness of AA6061 alloy are recovered to the values of the as-received alloy. The maximum expansion ratio（MER） of AA6061 tube increases by 25.5% and the material properties of formed tube reach the performances of raw material.

Characterization of A390 aluminum alloy produced at different slow shot speeds using vacuum assisted high pressure die casting

The effects of vacuum assistance on the microstructure and mechanical properties of high pressure die cast A390alloy at different slow shot speeds were evaluated.Plate-shaped specimens of hypereutectic A390aluminum alloy were produced on a TOYO BD?350V5cold chamber die casting machine incorporated with a self-improved TOYO vacuum system.According to the results,the vacuum pressure inside the die cavity increased linearly with the increasing slow shot speed at the beginning of mold filling.Meanwhile,tensile properties of vacuum die castings were deteriorated by the porosity content.In addition,the average primary silicon size decreased from23to14μm when the slow shot speed increased from0.05to0.2m/s,which has a binary functional relationship with the slow shot speed.After heat treatment,microstructural morphologies revealed that needle-shaped and thin-flaked eutectic silicon particles became rounded while Al2Cu dissolved intoα(Al)matrix.Furthermore,the fractography revealed that the fracture mechanism has evolved from brittle transgranular fracture to a fracture mode with many dimples after heat treatment.

基于超高压处理的猕猴桃原浆制备研究

为优化猕猴桃超高压灭菌条件下原浆制作工艺,对3种不同原浆制作工艺分别进行单因素优化试验,筛选出两种产品色泽和稳定性较好的工艺,并对这两种工艺所制作样品进行4℃储藏40 d的品质对比。结果表明,在最大程度保留猕猴桃原浆绿色,提高其稳定性的条件下,3种工艺的优选次序为:对辊式挤压制浆>胶体磨制浆>高压微射流制浆;与胶体磨工艺相比,对辊式挤压工艺制作的产品在4℃条件下储藏30 d内无明显的自然分层,产品VC损失较少;优化后的制浆工艺为:采用对辊式挤压工艺,挤压次数为1次。按照该工艺制作的猕猴桃原浆色泽相对均一,以青绿色为主,VC含量为40~50 mg/100 g。

高压二氧化碳处理对桑椹原汁杀菌效果和品质稳定性的影响

为探讨高压二氧化碳处理(HPCD)对桑椹原汁杀菌效果的影响,以温度、压力、时间为自变量,以菌体致死率和褐变度为因变量,通过单因素和响应面试验优化最佳杀菌条件.结果表明,温度、压力均对桑椹原汁杀菌效果有显著影响,当压力为30 MPa,时间49 min,温度48℃,菌体致死率能达到4.10,在此条件下处理的桑椹原汁25℃贮藏60 d后,其花色苷含量、白藜芦醇含量、褐变度、菌落总数、 Vc含量、风味均优于传统热杀菌处理的桑椹原汁.结论:HPCD可实现在温和条件下对桑椹原汁达到理想的杀菌效果,同时能有效延长其保质期.

超高压力场下不同含量酒精对淀粉结构与理化性能的影响

本研究探讨了不同压力场(200、400、600 MPa)与不同含量酒精(30%~100%)作用下淀粉多尺度结构和理化性能的变化规律,旨为揭示超高压处理过程中溶液极性变化诱导淀粉多尺度结构转变进而调控其理化特性的分子机制。采用扫描电镜、小角X射线散射、X射线衍射、快速黏度分析等研究了不同压力场下溶液酒精含量对淀粉颗粒结构、层状结构、结晶结构以及糊化与老化特性的影响规律。结果发现,纯水相中的淀粉颗粒在600 MPa压力时,其颗粒态、层状及结晶结构破坏严重,淀粉糊峰值粘度次递下降;而在含有30%~100%酒精的溶液体系中,淀粉有序化结构向无序化形态的转变受到明显抑制,但其峰值粘度呈现无规律变化趋势。此外,超高压处理过程中溶液的酒精成分还可明显延缓淀粉糊的老化行为,且老化淀粉的结晶度与淀粉糊的回生值呈现较强正相关关系。综上,研究结果将为基于超高压与溶液极性处理定向调控淀粉结构与功能特性提供理论指导。

镇痛镇静治疗对神经外科重症监护室患者颅内压及预后的影响研究

研究了镇痛镇静治疗对神经外科重症监护室(neurosurgical intensive care unit,NICU)患者颅内压及预后的影响。以接受不同治疗方法的NICU外伤性高颅压患者为例,比较了观察组和对照组患者的镇痛镇静效果、颅内压、意识状态、神经功能以及预后情况。结果表明,观察组VAS评分、Ramsay评分、颅内压、NIHSS评分均低于对照组,GCS评分均高于对照组,预后情况的有效率高于对照组,P<0.05。由此可见,联合应用镇痛镇静治疗对于神经重症监护室的患者是有效的,能降低患者的颅内压,减轻昏迷程度,改善NICU患者的神经功能,对患者康复预后有积极影响。

全方位优质护理在小儿鼻腔负压冲洗中的应用

目的探讨小儿鼻腔负压冲洗过程中采用全方位优质护理对临床效果的影响。方法选取2021年12月至2022年3月我院收治的共计86例行鼻腔负压冲洗的患儿,采用随机摸球法分成干预组(n=43)与对照组(n=43)。对照组采用常规护理干预,干预组采用全方位优质护理干预,对两组治疗依从性(治疗依从性调查问卷)、症状缓解、舒适度[舒适状况量表(GCQ)]、睡眠质量[匹兹堡睡眠质量指数量表(PSQI)]、家长护理总满意度[纽卡斯尔护理满意度量表(NSNS)]进行比较。结果干预组(95.35%)治疗依从性较对照组(79.07%)高(P<0.05);干预组症状(鼻塞、鼻痒、流涕、打喷嚏)缓解时间较对照组短(P<0.05);干预后两组GCQ评分提高(P<0.05),PSQI评分降低(P<0.05),与对照组比较,干预组GCQ评分高(P<0.05),PSQI评分低(P<0.05);干预后两组NSNS评分提高(P<0.05),干预组评分较对照组高(P<0.05)。结论全方位优质护理应用于小儿鼻腔负压冲洗中,可增强治疗依从性,促进临床症状缓解,提高舒适度、睡眠质量及家长满意度。