Effect of cold working and sandblasting on the microhardness, tensile strength and corrosion resistance of AISI 316L stainless steel

The aim of this work is to investigate the effect of cold working and sandblasting on the microhardness, tensile strength and corro-sion rate of AISI 316L stainless steel. The specimens were deformed from 17% to 47% and sandblasted for 20 min using SiC particles with a diameter of 500-700 μm and an air flow with 0.6-0.7 MPa pressure. The microhardness distribution and tensile test were conducted and a measurement on the corrosion current density was done to determine the corrosion rate of the specimens. The result shows that the cold working enhances the bulk microhardness, tensile and yield strength of the specimen by the degree of deformation applied in the treatment. The sandblasting treatment increases the microhardness only at the surface of the specimen without or with a low degree of deformation. In addition, the sandblasting enhances the surface roughness. The corrosion resistance is improved by cold working, especially for the highly deformed specimen. However the follow-up sandblasting treatment reduces the corrosion resistance. In conclusion, the cold working is prominent to be used for improving the mechanical properties and corrosion resistance of AISI 316L stainless steel. Meanwhile, the sandblasting subjected to the cold worked steel is only useful for surface texturing instead of improving the mechanical properties and corrosion resistance.

Bridge Maintenance Robotic Arm:Mechanical Technique to Reduce the Nozzle Force of a Sandblastine Rig

This paper describes a mechanical technique to reduce the nozzle reaction force of a sandblasting rig. A theoretical evaluation of the magnitudes and direction of action of typical sandblasting nozzle forces has been conducted and a technique for exploiting available energy in order to reduce the magnitude of the forces at the nozzle has been developed.Experimental results from a variety of tests in different configurations have confirmed the theoretically determined force magnitude’s accuracy and shown that forces of up to 106N can be present in typical sandblasting operations. The results have also shown that an up to 77% reduction of force at the nozzle can be achieved by applying the developed mechanicaltechnique.

Fuji "Sandblaster" 儿童自行车

Fuji “Sandblaster”系为一种价廉物美(市场售价仅为479马克)、不配备Stvzo(德国城市交通总则)所规定的装备件、规格为20英寸、专供少男少女使用的儿童MTB自行车新品。该车同样配有一种外观造型呈Y形、高度达28公分的钢制车架,可供少男少女从5岁起一直“享用”

Levi Strauss and H&M Announce Ban on Sandblasting

As a commitment to the health and safety of workers across the apparel industry, Levi Strauss & Co. and Hennes & Mauritz AB (H&M) announced plans to implement a global ban on sandblasting in all of their future

Improving the Surface Roughness of Dental Implant Fixture by Considering the Size,Angle and Spraying Pressure of Sandblast Particles

In this study,different conditions of sandblasting on dental implant fixtures were investigated to achieve the best sandblasting conditions.18 different sandblasting conditions(Using 152 implant fixture samples)were examined,including parameters such as particle size,particle blasting pressure,and particle blasting angle.The surface treatment of the samples was performed using the SLA+Anodizing method.AFM testing was performed for each of the 18 different states,and the average surface roughness of each of these was compared with each other.Then,a bone layer was placed on the sample with the closest average surface roughness to the standard and the least amount of aluminum oxide on its surface among the 18 different states,to confirm the accuracy and quality of the desired surface roughness by examining the bone formation process and speed.The results showed that state No.4(sandblast particle size:75µm,spraying pressure of sandblast particles:4 bar,sandblast particle spraying angle:30 degrees),which was prepared using the SLA+Anodizing method and had a surface roughness of 1.989µm(The percentage of Al_(2)O_(3)on the surface=6%),had the best sandblasting conditions and showed 95%cell viability and accelerated the treatment and bone formation process for about a week.The simulation results,using Abaqus software,indicated that the stress distribution on the surface of the implant fixture in contact with the bone surface has increased by approximately 4.3%for state No.4.This will help prevent loosening of the dental implant fixture over time.

Surface and Subsurface Defects Studies of Dental Alloys Exposed to Sandblasting

The defects created in commercial dental alloys during blasting with alumina particles propelled in compressed air under pressure 0.1 and 0.4 MPa have been studied using positron annihilation spectroscopy, scanning electron microscopy and X-ray diffraction. It was observed that higher pressure causes the increase in roughness and damaged zone range. The type of defects was determined as vacancies on dislocations. The defect concentration decreases with the depth and depends on alloys' type and applied pressure. The Rutherford backscattering spectroscopy and variable energy positron beam studies indicate shallow alumina deposition in material and show that small pressure of 0.1 MPa is not enough to remove metal surface oxides completely in 60 s in all studied dental alloys.

Ductility of copper films on sandblasting polyimide substrates

Different surface morphologies of polyimide(PI)foils widely applied in flexible electronics were obtained using the technique of sandblasting.Copper(Cu)films were subsequently deposited on the treated surface of PI substrates.Upon tensile loading, the critical strain,crack density and count of cracks were measured to examine the ductility of Cu films on PI substrates.Obtained results show that after sandblasting treatment,the critical strain of Cu film decreases from 8.0%to 6.9%and,in comparison with the case without sandblasting,its surface crack density decreases remarkably,with no saturation of the crack density.The reduced crack density is attributed to the increase of contact area and interfacial adhesion after sandblasting,and whether the crack density is saturated or not is dependent upon the morphology of the cracks formed as a function of tensile strain.

Mechanical strength of soda-lime glass sandblasted by gravitation

Damage to a glass surface by sandblasting has a remarkable effect on its mechanical properties and strength.In this study,we analyze the superficial deterioration of soda-lime glass and its influence on the mechanical strength.Sandblasting by gravitation from a fixed height causes damages by the free fall of different quantities of sand,which we performed for a selected grain size and at different angles of inclination.To characterize the surface state,we used different roughness measures(the arithmetic mean value of the roughness Ra,the root mean square roughness Rq,and the maximum roughness Rmax)and measured the optical transmission(transmittance)at different points on the specimen surface using a profilometer.To determine the mechanical strength,we proceeded by two methods:first,by a shock ball(falling ball),and then by biaxial bending using circular supports.The effects of the surface damage on the optical transmission and the mechanical strength of the glass are graphically presented and discussed in this paper.

Wear calculation of sandblasting machine based on EDEM-FLUENT coupling

Sandblasting machines are widely used in chemical,mechanical and other engineering fields.The internal flow field of the sandblasting machine belongs to a complex gas-solid two-phase flow,and impact by the continuous abrasive sand can cause the machine to wear or even fail.In this study,the EDEM-FLUENT coupling method was used to calculate the transient flow field of the gas phase and the motion,dynamic and collision characteristics of the sand.Air in the sandblasting machine was treated as the ideal gas and the continuous phase.The sand was regarded as the discrete phase solid in the computation.Using the Archard wear model,the wear amount of the sandblasting machine was calculated and the wear law was analysed,to provide a theoretical basis for optimising the design and operation method of the blasting machine.

Wear calculation of sandblasting machine based on EDEM-FLUENT coupling

Sandblasting machines are widely used in chemical, mechanical and other engineering fields. The internal flow field of the sandblasting machine belongs to a complex gas-solid two-phase flow, and impact by the continuous abrasive sand can cause the machine to wear or even fail. In this study, the EDEM-FLUENT coupling method was used to calculate the transient flow field of the gas phase and the motion, dynamic and collision characteristics of the sand. Air in the sandblasting machine was treated as the ideal gas and the continuous phase. The sand was regarded as the discrete phase solid in the computation. Using the Archard wear model, the wear amount of the sandblasting machine was calculated and the wear law was analysed, to provide a theoretical basis for optimising the design and operation method of the blasting machine.

内窥镜辅助龈下刮治联合赤藓糖醇龈下喷砂治疗种植体周围炎的疗效评价

目的:研究内窥镜辅助龈下刮治联合赤藓糖醇龈下喷砂技术治疗种植体周围炎的临床疗效,为种植体周围炎的有效治疗提供理论依据。方法:选择本院牙周科就诊并接受治疗的种植体周围炎患者,按就诊时间共有58例种植体周围炎患者陆续进入观察,按随机数字表法分为对照组(28例)和微创组(30例);对照组患者采用传统盲视龈下刮治治疗,微创组患者采取内窥镜辅助龈下刮治联合赤藓糖醇龈下喷砂治疗。分析2组患者治疗前后探诊深度(PD)、改良菌斑指数(mPLI)和改良龈沟出血指数(mSBI)以及龈沟液中白细胞介素1β(IL-1β)、白细胞介素6(IL-6)和肿瘤坏死因子α(TNF-α)水平。结果:治疗前2组患者PD、mPLI和mSBI及龈沟液中IL-1β、IL-6和TNF-α水平比较差异无统计学意义(P>0.05),具有可比性。治疗后2组患者PD、mPLI和mSBI,龈沟液中IL-1β、IL-6和TNF-α水平均较治疗前明显下降(P<0.05)。与对照组比较,微创组患者治疗后PD、mPLI和mSBI明显降低(P<0.05);龈沟液中IL-1β、IL-6和TNF-α水平也明显降低(P<0.05)。结论:在短期内采用内窥镜辅助龈下刮治联合赤藓糖醇龈下喷砂技术治疗种植体周围炎更有助于控制种植体周围组织的炎症,改善临床症状。

喷砂工艺对Y-TZP力学性能和表面粗糙度的影响

为了评估不同喷砂工艺对氧化锆陶瓷力学性能和表面粗糙度的影响,采用不同的喷砂处理工艺对样品进行喷砂处理。研究表明氧化锆陶瓷经过喷砂处理后表层单斜相含量明显增加。喷砂原料的颗粒尺寸越大,相变越多。喷砂后表面粗糙度增加,在相同的喷砂条件下,经球形Al_(2)O_(3)处理的样品表面粗糙度Sa远小于经SiC颗粒处理的。在喷砂原料粒径为100μm、喷砂时间为20 s、压力为0.2 MPa的情况下,四点弯曲强度分别提高了27%(SiC)与21%(Al_(2)O_(3))。因此,具有球形颗粒形貌的Al_(2)O_(3)颗粒更适合用作表面喷砂处理。

喷砂处理钢板高强度螺栓摩擦型连接循环抗剪试验研究

为了解决地震下高强度螺栓抗剪连接承载力性能的问题,对钢板喷砂处理的不同螺栓尺寸和孔型的36个高强度螺栓抗剪连接件进行了双剪、单剪和夹紫铜片双剪的循环加载试验,获得了连接件抗剪承载力、抗滑移系数、滑移前变形、刚度、滑移后的滑动承载力、实测摩擦因数、名义摩擦因数和螺栓拉力。结果表明:双剪连接刚度大,单剪连接滑移前变形是双剪连接的1.8倍;在喷砂钢板间夹紫铜片后抗滑移系数提高约16.1%并可减小摩擦力离散性和滑移噪声;螺栓垫圈与喷砂钢板间的摩擦力对单剪抗剪承载力有提高作用;提出修正的单剪连接抗滑移承载力公式;给出双剪、单剪和夹紫铜片双剪连接的滑移前变形建议取值,提出3类连接的滑动承载力公式。

压裂管柱防管内溢流工具的研制与应用

目前,在油水井常规起下油管作业过程中,通常会采用压井措施,由于压后地层压力大,井下压力高,井口油管内会溢出大量污油污水,既给地下油层带来污染也给生态环境造成破坏,并给员工的工作环境以及员工身体造成一定伤害。随着人们对环境越来越重视,其压裂管柱方对有关内溢流的研制成为解决问题的主要方向。针对常规压裂施工时,发现喷砂器滑套没有到位,导致出砂口未堵住,使油管外液体进入油管内,无法密封下级喷砂器的出砂口,产生井口油管内溢流。除此之外,压裂施工后最上级喷砂器无滑套密封其出砂口,也产生油管内溢流。针对以上问题,设计出一种新型喷砂器及其配套工具,使得其出砂口随压随关闭,利用关闭出砂口达到具有多层压裂、压后滑套均到位、锁定,达到了防油管内溢流的目的。

磨粉机磨辊表面磨损特征提取与识别

目的:预测磨粉机喷砂辊使用寿命。方法:通过搭建的图像采集系统对磨辊表面的磨损图像进行采集,基于灰度共生矩阵算法,获得磨辊磨损周期内的二阶矩、熵值、对比度和相关性等纹理参数,将获得的纹理特征参数输入构建的基于粒子群算法(PSO)的LS-SVM模型,最终对喷砂辊的磨损寿命进行预测。结果:粒子群算法可以很好地优化LS-SVM的惩罚因子和核参数,PSO-LS-SVM算法要远远优于LS-SVM算法模型,采用PSO-LS-SVM算法可以准确地识别磨粉机喷砂辊表面的磨损状态。结论:该系统可以准确地预测喷砂辊的使用寿命。

喷砂压力对钛合金镀层缺陷的影响

航空航天等钛合金关键部件的镀层缺陷问题一直是研究热点。针对钛合金母材喷砂处理导致镀铬层缺陷严重的问题,研究了喷砂参数对钛合金镀层缺陷的影响。并采用磁粉检测、金相显微镜、能谱仪和扫描电镜等对镀层缺陷形成原因进行分析,给出喷砂参数建议。试验结果表明,钛合金在喷砂处理时,会使白刚玉砂镶嵌到钛合金母材表面,导致镀层与母材结合力差并发生开裂。采用100目(150μm)白刚玉砂,0.4 MPa喷砂压力,可以有效改善白刚玉砂在母材表面的残留现象,为获得高质量钛合金镀层的母材喷砂参数的选择提供了指导。

碱热处理纯钛表面纳米改性后对成骨细胞早期黏附生长的影响

背景:纯钛表面纳米结构改性是钛种植体表面处理研究的热点领域。目的:评价碱热处理纯钛表面纳米改性后对成骨细胞早期黏附生长的影响。方法:取直径15 mm、厚度1.5 mm的四级纯钛片,分3组处理:光滑处理组经250目、800目、1500目碳化硅砂纸逐级打磨抛光;喷砂酸蚀处理组在0.45 MPa气压下用100μm的Al2O3颗粒对光滑处理后的钛片进行喷砂处理,然后进行酸蚀处理;碱热处理组将经过光滑处理的钛片置于反应釜内,加入10 mol/L NaOH溶液浸没钛片,置于100℃烘箱中加热12 h。检测3组钛片的表面形貌、粗糙度及亲水性。将成骨细胞MG63分别接种于3组钛片表面,免疫荧光染色观察细胞黏附情况。结果与结论:①扫描电镜显示,光滑处理组钛片表面带有均匀的划痕,喷砂酸蚀处理组钛片表面凹凸不平,碱热处理组钛片表面形成均匀一致的纳米级三维孔洞形貌;喷砂酸蚀处理组、碱热处理组钛片的粗糙度值大于光滑组(P<0.05),水接触角低于光滑处理组(P<0.05);②MG63细胞接种3,6 h后的免疫荧光染色显示,喷砂酸蚀处理组、碱热处理组钛片表面的黏附细胞数量高于光滑处理组(P<0.05);接种12 h后的免疫荧光染色显示,相对于光滑处理组,喷砂酸蚀处理组和碱热处理组钛片表面的细胞肌动蛋白骨架更加伸展,大部分细胞伸出较粗壮的伪足,利于后续细胞间信号传导和细胞间相互作用;③结果表明,碱热处理可在钛片表面制备出具有一定生物活性的纳米结构,有利于成骨细胞的早期黏附。

基材表面处理方式对油管内涂层的性能影响研究

随着防腐防蜡的涂层油管在油田中被广泛应用,油管涂覆技术已成为研究热点。为了研究基材不同处理方式对涂层性能的影响,对油管内表面进行喷砂和化学除锈处理,选用无溶剂环氧涂料进行涂覆,对涂层进行表面观察,并对其塑韧性、耐腐蚀性等性能进行检测。实验结果表明:喷砂后材料表面冲蚀坑大小均匀,粗糙度可以达到39.069μm;化学除锈表面出现成片腐蚀,粗糙度为15.145μm,涂层粗糙度仅为2.037μm。两种处理方式涂层的附着力均满足使用要求,但喷砂后的附着力比除锈后的附着力高45%;对涂层进行弯曲、疲劳等性能评价后,涂层均未出现开裂和漏点等现象;经高温高压腐蚀后,化学除锈后试样表面出现鼓泡,但喷砂后材料表面未出现变化。

具射流反作用力喷砂除锈并联机构自抗扰控制

针对由喷砂除锈并联机构末端喷枪射流反作用力造成的非匹配干扰问题,提出一种喷砂除锈并联机构非线性自抗扰控制方法。采用解析法对并联机构进行运动学分析,采用拉格朗日法建立考虑非匹配干扰的并联机构动力学模型;通过应用等效输入干扰技术将系统的非匹配干扰转换为位于控制输入通道的匹配干扰,并与建模误差、关节摩擦力及外部干扰等集总为系统总干扰;设计非线性扩张状态观测器对系统集总干扰进行实时精确估计和补偿,进一步设计基于扩张状态观测器的自抗扰控制,以增强系统对集总干扰的鲁棒性,同时提高其轨迹跟踪控制性能。最后证明闭环系统的稳定性,并基于MATLAB软件和具射流反作用力喷砂除锈并联机构样机,对所提出控制方法进行仿真和样机实验,实验结果验证了所提出方法的有效性。

凡尔喷砂器实现管内防喷环保压裂施工

当压裂施工完成后,常规起下油管管柱作业过程中,井口油管内会喷出返排液,其中有大量污油污水落地,对生态环境造成了污染,且喷出后回收难度大,容易造成二次污染。目前,大庆油田长垣内部采用封堵“侧壁出口”的防喷方式应用效果不理想,经常发生返排液溢出的事故。随着人们对环境越来越重视,其压裂管柱油管内溢流的控制成为重要解决问题。基于此对最新的研究成果进行归纳整理,首先分析压裂管柱管内喷液问题的主要原因、防喷工艺的设计难点,其次归纳出主要的封堵思路,具体针对压裂管柱油管内防喷的技术难点设计了新型凡尔喷砂器,将凡尔功能由原来的压前承压、压缩弹簧、压后密封喷砂口重新定位为压前承压、压缩弹簧两项,杜绝了喷砂器出砂口密封执行部件磨损严重导致油管内喷液的现象。进行现场试验15口井,共节约环保费用530.1万元。为大庆油田的油管内防喷技术提供了确实可行的解决办法。