Surface Roughness Modification of Free Standing Single Crystal Silicon Microstructures Using KrF Excimer Laser Treatment for Mechanical Performance Improvement

Single crystal silicon freestanding structures for tensile and fatigue testing were treated with KrF excimer laser to improve surface roughness and accordingly mechanical performance. Sample thickness was 5 μm. Localized laser treatment was successful in eliminating the scallops developed during Bosch process and in reducing surface roughness. Harsh irradiation at laser energies up to 4 J/cm2 was only possible due to localized treatment without significant vibrations occurring on the freestanding samples that led to fracture in preliminary experiments at energies as low as 0.16 J/cm2. Finite element analysis was used to investigate the temperature distribution on the irradiated structures. Atomic force microscopy (AFM) and Raman spectroscopy were also used to assess surface roughness, crystallinity changes and surface stresses developing on surfaces subjected to perpendicular laser irradiation. At a high energy (3.2 J/cm2) the top surface showed a decrease of roughness compared to fabricated samples. Raman spectroscopy showed the dominance of crystalline silicon after laser irradiation. The effects of laser energy, number of

An Evaluation of Manure Management Strategies, Phosphorus Surface Runoff Potential and Water Usage at an Arkansas Discovery Dairy Farm

Manure management is an essential component of dairy production. Nutrient-laden, field-applied dairy manure often serves as a fertilizer source, but can also pose environmental threats if not properly managed. The Haak dairy farm, located in Decatur, Arkansas, was granted a permit by the Arkansas Department of Environmental Quality (ADEQ) to employ a unique method in treating and storing cattle manure generated during the milking process. This method includes minimizing water use in wash water, dry scraping solids to combine with sawdust for composting and pumping effluent underground into a sloped concrete basin that serves as secondary solid separator before transporting the manure effluent into an interception trench and an adjacent grassed field to facilitate manure nutrient uptake and retention. The Arkansas Discovery Farm program (ADF) is conducting research to evaluate the environmental performance of the dairy’s milk center wash water treatment system (MCWW) by statistical analysis, characterization of phosphorus (P) migration in soil downslope from the inception trench, temperature measurements, and nutrient analysis of a stored dry stack manure/sawdust mixture. Goals included determining possible composting effectiveness along with comparisons to untreated dairy manure and quantifying the use of on-farm water. Results from this research demonstrated that: 1) The MCWW was effective at retaining manure-derived nutrients and reducing field nutrient migration as the MCWW interception trench had significantly higher total nitrogen (TN) (804.2 to 4.1), total phosphorus (TP) (135.6 to 1.5), and water extractable phosphorus (WEP) (55.0 to 1.0) concentrations in milligrams per liter (mg⋅L-1) than the downhill freshwater pond respectively;2) temperature readings of the manure dry stack indicated heightened levels of microbial and thermal activity, but did not reach a standard composting temperature of 54°C;3) manure dry stack nutrient content was typically higher than untreated dairy manure when measured on a “dry basis” in ppm, but was lower on an “as is basis” in ppm and kg/metric ton;and 4) water meter readings showed that the greatest use of on-farm water was for farm-wide cattle drinking (18.77), followed by water used in the milking center (3.45) and then followed by human usage (0.02) measured in cubic meters per day (m3⋅d-1). These results demonstrate that practical innovations in agricultural engineering and environmental science, such as the Haak dairy’s manure treatment system, can effectively reduce environmental hazards that accompany the management of manure at this dairy operation.

NH_3 Plasma Surface Treatments of Engineering Fluoropolymers: A Way to Enhance Adhesion of Ni or Cu Thin Films Deposited by Electroless Plating

This paper describes the electroless Ni or Cu plating of some fiuoropolymer substrates through a tin-free activation process. Materials subjected to surface metallization are commercial Teflon() FEP, Nafion(), ACLAR() and LaRCTM-CP1 thin films which have recently gained a large scientific and technological interest due to their excellent thermal, chemical, mechanical and dielectric properties. The original approach implemented in the present work involves: (i)the grafting of nitrogen-containing functionalities on the polymer surfaces through plasma treatments in ammonia, (ii) the direct catalysis of the so-modified surfaces via their immersion in a simple acidic PdCl2 solution (i.e. without using a prior surface sensitization in an acidic SnCl2 solution), and finally (iii) the electroless metallization itself. However, prior to the immersion in the industrial plating baths, the chemical reduction of the Pd+2 species (species covalently tethered on the nitrogen-containing groups) to metallic palladium (PdO) is shown to be a key factor in catalyzing the electroless deposition initiation. This is made by immersion in an hypophosphite (H2PO2-) solution. Wettability measurements and X-ray photoelectron spectroscopy (XPS) experiments are used to characterize every surface modification step of the developed process. A cross-hatch tape test was used to asses the adhesion strength of the electroless films that is shown qualitatively good. In addition, a fragmentation test was developed in combination with electrical measurements. Its use allows to distinguish different adhesion levels at the metal/polymer interface and to evidence the influence of some processing parameters.

Study on the Effect of Surface Modification on the Mechanical and Thermal Behaviour of Flax,Sisal and Glass Fiber

Natural fiber-reinforced hybrid composites can be a better replacement for plastic composites since these plastic composites pose a serious threat to the environment.The aim of this study is to analyze the effect of surface modification of the natural fibers on the mechanical,thermal,hygrothermal,and water absorption behaviors of flax,sisal,and glass fiber-reinforced epoxy hybrid composites.The mechanical properties of alkaline treated sisal and flax fibers were found to increase considerably.Tensile,flexural and impact strength of glass/flax-fiber-reinforced hybrid samples improved by 58%,36%,and 51%,respectively,after surface alkaline treatment.In addition,the hygrothermal analysis and water absorption capacity are studied and also the Interfacial bonding properties were analyzed using Scanning Electron Microscopic images.The thermal analysis using thermogravimetric analyzer reveals that the decomposition temperature for hybrid fiber reinforced composites are between 306 and 312℃.In conclusion,surface treatment improves the performance of natural fiber in hybrid fiber-reinforced composites,particularly flax fiber.

TP2铜管精整工序喷墨质量不良原因分析及改进措施初探

在精密铜管精整复绕工序中,涡流探伤装置检测到伤点后会向喷墨装置发送信号,以对铜管表面缺陷进行喷墨标记,但是该过程普遍存在喷墨不良,严重影响了对缺陷的判断。本文介绍了TP2铜管生产线中涡流探伤仪器的工作原理,对原有的涡流探伤仪器、喷墨装置以及喷枪结构进行调研,分析了原有喷墨装置喷墨时存在的漏墨和拖墨问题,探讨了等离子技术与激光刻蚀技术作为喷墨技术替代方案的可能性。文献调研、现有技术分析及其他替代试验的结果表明,采用等离子体表面处理技术对已喷墨铜管进行处理后,可以一定程度地改善铜管拖墨的问题;采用功率为300 W的激光对铜管表面进行刻蚀处理,激光头速度分别为80 mm/s和200 mm/s时,对铜管表面刻蚀呈现出的不同效果,均能够进行缺陷的有效标识。因此,铜管表面激光刻蚀技术可以作为喷墨技术的替代方案。

Improvement of titanium alloy TA19 fatigue life by submerged abrasive waterjet peening:Correlation of its process parameters with surface integrity and fatigue performance

Submerged abrasive waterjet peening(SAWJP)is an effective anti-fatigue manufacturing technology that is widely used to strengthen aeroengine components.This study investigated the correlation of SAWJP process parameters on surface integrity and fatigue life of titanium alloy TA19.SAWJP with different water pressures and standoff distances(SoDs)was conducted on the TA19 specimens.The surface integrity of the specimens before and after SAWJP with different process parameters was experimentally studied,including microstructure,surface roughness,microhardness,and compressive residual stress(CRS).Finally,fatigue tests of the specimens before and after SAWJP treatment with different process parameters were carried out at room temperature.The results highlighted that the fatigue life of the TA19 specimen can be increased by 5.46,5.98,and 6.28 times under relatively optimal process parameters,which is mainly due to the improved surface integrity of the specimen after SAWJP treatment.However,the fatigue life of specimens treated with improper process parameters is decreased by 0.55 to 0.69 times owing to the terrible surface roughness caused by the material erosion.This work verifies that SAWJP can effectively improve the surface integrity and fatigue life of workpieces,and reveals the relationship between process parameters,surface integrity,and fatigue life,which provides support for the promotion of SAWJP in the manufacturing fields.

基于Moldflow的机箱下盖注射模优化设计

以机箱下盖为研究对象,通过Moldflow软件对其进行填充、保压和翘曲分析,优化了浇口位置,采用正交试验法优化了成型工艺。根据优化结果确定了型腔布局和流道尺寸,以UG软件对模具进行设计,并阐述了主分型面设计、抽芯结构设计和镶件设计,对模具结构和工作过程进行了论述。经实际生产验证:模具结构合理、动作可靠,成型的制品尺寸合格且性能良好。

界面处理对预制UHPC与现浇NC界面抗剪性能的影响

对未处理和经喷砂、凿毛、切槽界面处理后的预制超高性能混凝土(UHPC)与现浇普通混凝土(NC)组合试件进行双面剪切试验,记录加载过程中的剪切荷载与界面滑移,通过剪切荷载-界面滑移曲线分析不同界面处理方式对组合试件抗剪性能的影响.结果表明:界面处理显著提高了预制UHPC与现浇NC组合试件的界面抗剪性能;不同界面处理方式下组合试件的破坏模式主要分为3种;采用边长18 mm正方形钢丝网格凿毛处理的组合试件界面抗剪强度与抗剪刚度均最大,其界面抗剪强度为未处理界面试件的4.69倍;凿毛与切槽处理使组合试件拥有较好的界面抗剪性能,表现为延性破坏;界面粗糙度相近但界面处理方式不同的组合试件抗剪性能表现出明显差异;各组试件界面抗剪强度与抗剪刚度变化趋势大致相同.

瞬态面波法在夯实地基检测中的应用

强夯地基处理是一种常用的地基加固方法,其检测效果至关重要。瞬态面波法作为一种高效、非破坏性的地基检测方法,在强夯地基检测中具有广泛的应用前景。本文通过对两个实例进行总结分析,单纯的浅层平板载荷试验因其主要应力影响范围有限,不能有效全面反应整个场地的承载力情况。而通过采用瞬态面波法对场地强夯前、后进行检测,得到定性评价场地处理效果,再依据瞬态面波检测异常区域针对性进行载荷试验定量检测,得到瞬态面波与载荷试验之间的联系,从而大幅提高检测效率及检测结果可靠性。

大功率风电轴承技术进展

面向国家“双碳”战略,风电装备向更大功率方向迅速发展,也对大功率风电装备中不同类型和系列的滚动轴承提出了大型化、长寿命、高可靠性、智能化和高效运行等更高的技术要求。本文评述大功率风电轴承技术发展的现状、趋势和关键内容,涉及轴承数字化设计、材料与热处理、高性能制造、智能装配、检验测试与试验、智能运维等多个方面,以期为大功率风电轴承产业发展提供参考。

专用预埋钢绞线吊件力学性能试验研究

为研究专用预埋钢绞线吊件与混凝土之间的粘结锚固强度,考虑不同锚固长度、弯折角度、末端形式对承载力的影响。对专用预埋钢绞线吊件进行了与混凝土粘结锚固强度的试验、三种拉拔承载力试验以及与圆钢吊环试验对比试验。通过试验确定了预埋钢绞线吊件与混凝土之间的粘结锚固强度。结果表明:钢绞线吊件的锚固长度达到40d(d为钢铰线直径)以上时,粘结锚固力会大于吊件强度,使钢绞线吊件发生屈服破坏,钢绞线吊件的弯折角度在120°~150°中间对钢绞线吊件承载力基本没有影响,钢绞线吊件的末端经过处理后破坏形态由脆性变为延性且承载力有所增加。结果表明,钢绞线吊件具有良好的力学性能,钢绞线吊件在承载力方面优于圆钢吊环。

脱机试验拔管后行面罩雾化对呼吸机支持治疗患者血气分析指标及拔管成功率的影响

目的:分析脱机试验拔管后行面罩雾化对呼吸机支持治疗患者血气分析指标及拔管成功率的影响。方法:选取本院2019年1月至2022年3月行呼吸机支持治疗的80例患者,依据脱机试验拔管后是否使用面罩雾化进行分组,对照组40例未使用面罩雾化并进行传统护理,观察组40例在传统护理基础上使用面罩雾化。分别在脱机试验拔管后、成功拔管后采集血气指标,收集吸痰次数、呛咳次数、痰痂次数、一次拔管成功率、并发症总发生率并进行对比。结果:两组脱机试验拔管后的血气分析指标相近,两组成功拔管后的血气分析指标均优于本组脱机试验拔管后(P<0.05),且观察组的血气分析指标优于对照组(P<0.05);观察组的吸痰次数、呛咳次数、痰痂次数均少于对照组(P<0.05),一次拔管成功率明显高于对照组(P<0.05),并发症总发生率低于对照组(P<0.05)。结论:脱机试验拔管后行面罩雾化有助于改善呼吸机支持治疗患者血气分析指标,提高一次拔管成功率并降低并发症总发生率,吸痰次数、呛咳次数、痰痂次数均更少。

零件荧光渗透检测典型显示实例分析

零件经荧光渗透检测时,表面常呈现各种形态的荧光显示。这些显示是由在役使用、加工成型及表面处理等多种因素形成的。为使零件在荧光渗透检测中结果可靠,该文对在役的零件受力及服役情况进行分析,并对零件的荧光显示特征总结,浅谈荧光渗透检测技术在零件检测上的应用,有利于产品荧光渗透检测技术的提升。在实际检测中,往往需要操作人员对荧光显示特征有清晰的认识和辨别的能力,因此操作人员对荧光显示的判断与分析在荧光渗透检测中起着至关重要的作用。

硅烷偶联剂改性钢纤维的性能

为改善钢纤维与混凝土基体间的结合作用,本文以γ-氨丙基三乙氧基硅烷(KH-550)和硅酸四乙酯(TEOS)为基底制备改性溶液,采用溶胶-凝胶法对钢纤维进行改性,通过控制改性溶液中硅烷偶联剂和硅酸四乙酯的相对比例作为对照进行改性纤维制备与试验,并通过纤维拉拔试验,从宏观角度对钢纤维与混凝土界面处黏结性能进行研究。结果表明:1)经过KH-550和TEOS复合溶液的改性作用,钢纤维表面粗糙度得到显著改善;2)当KH-550和TEOS的比例增加时,钢纤维拉拔试验结果会有所提升,之后会出现下降趋势,在相对比例为3:1时,改性钢纤维表面形貌良好、平整度高且附着力强,涂层效果最好。本文研究成果可为解决钢纤维在混凝土材料中强度利用率较低的问题提供一定的借鉴与参考。

基于表面能理论和拉拔试验的铁尾矿与沥青黏附性研究

文中采用表面能理论和改进拉拔试验对铁尾矿与沥青间的黏附性进行了试验研究.结果表明:铁尾矿的表面能与沥青间的粘附功均小于石灰岩和玄武岩;粘附功随集料中SiO_(2)含量的增加而减小;改进拉拔试验可以评价沥青与集料间的黏附性,铁尾矿与沥青间的黏结力明显小于玄武岩和石灰岩,铁尾矿与基质沥青、SBR改性乳化沥青蒸发残留物间界面破坏类型为组合失效,与SBS改性沥青间界面破坏类型的为沥青内聚力失效.

40CrNiMoA自锁螺母盐雾试验不合格原因分析研究

对某产品盐雾试验不合格的原因进行分析,利用试验验证的方法,通过优化表面处理加工工艺流程、调整加工参数,分析比较喷涂二硫化钼与浸涂二硫化钼的区别与优缺点,解决自锁螺母盐雾试验不合格的问题,提高产品性能的一致性及稳定性。

汽车金属零部件表面处理方法及试验方案

表面处理技术既能保持基体材料的原本特征,又可以赋予产品表面各种新的性能要求,以提升产品表面的物理和机械性能。文章阐述了汽车零部件制造领域常用的机械加工零件、冲压件、铸造件、锻造件等不同工艺生产金属零部件适用的表面处理方法,分析电镀、抛丸、喷砂、喷丸、喷涂处理后零部件应选择的试验方案,为需要进行表面处理的汽车金属零部件开发验证提供了参考和依据,以确保表面处理的效果与质量。

超高分子量聚乙烯纤维表面的铬酸处理及表征

针对超高分子量聚乙烯纤维表面粘接性差的缺点,采用铬酸对其进行了表面处理.根据处理温度与处理后纤维强力的损失的关系,以及不同处理温度下的纤维表面的电镜照片形貌确定了最佳的处理温度为85℃;根据处理过纤维与未处理的纤维的红外图谱的差异对铬酸处理的氧化机理进行了探讨,确定在纤维表面生成了羟基、羰基、羧基等极性的对纤维具有浸润性的基团;借助自行设计的单丝拔出实验装置以及压制复合材料测试其层间剪切强度,对纤维表面处理后的粘接性进行了表征,发现采用适当的纤维处理工艺、选择合适的树脂基体可以使纤维的粘接性提高60%以上.

地表预注浆加固公路隧道浅埋偏压破碎围岩效果分析

针对广福隧道一段浅埋偏压破碎围岩的实际情况,为提高围岩强度,降低围岩的通透水性能,改善隧道成拱的作用,进而达到保护水资源、保证工程安全之目的,提出了采用水泥单液浆和水泥水玻璃双液浆的地面高压预注浆处治措施,并通过数值计算和现场试验详细分析了处治效果。综合分析表明:注浆处理后,围岩完整程度和强度明显提高,隧道断面净空收敛和拱顶下沉稳定速度较快,最终变形值较小,初期支护和二次衬砌整体受力特征得到很大改善,注浆处治效果非常显著。

不同桩表面处理对玻璃纤维桩与牙本质粘结强度的影响

[目的]评价不同的桩表面处理对玻璃纤维桩表面形貌及其与牙本质粘结强度的影响。[方法]选择20颗尺寸近似的离体单根管前牙,常规根管治疗后去除牙冠,完成根桩牙体预备后,粘固MATCHPOST玻璃纤维桩至根管内。根据粘固前桩表面处理方法,将20颗离体牙随机均分至如下4组:氢氟酸组(HF组);二氯甲烷组(CH组);过氧化氢组(HO组);硅烷偶联剂组(S组)。用慢速金刚石切割机将每个牙根垂直于牙长轴切割出3个3 mm厚的片段作为测试样本。于万能材料试验机上对各组(n=15)样本加载直至纤维桩被完全推出。对实验数据进行单因素方差分析和多重比较,观察样本的破坏模式。[结果]4个实验组的粘结强度值(MPa)由高到低如下:HO组(10.00±3.17);CH组(7.98±2.46);HF组(6.15±1.87);S组(5.82±1.76)。除了HF组和S组比较差异无显著性意义外(P>0.05),每两组间比较差异均有显著性意义(P<0.05);样本的失败模式主要为混合破坏。[结论]用过氧化氢和二氯甲烷进行桩表面处理可提高玻璃纤维桩与牙本质的粘结强度。