Mechanical properties and fracture surface roughness of thermally damaged granite under dynamic splitting

In order to understand the mechanical properties and the fracture surface roughness characteristics of thermally damaged granite under dynamic splitting,dynamic Brazilian splitting tests were conducted on granite samples after thermal treatment at 25,200,400,and 600℃.Results show that the dynamic peak splitting strength of thermally damaged granite samples increases with increasing strain rate,showing obvious strain‐rate sensitivity.With increasing temperature,thermally induced cracks in granite transform from intergranular cracks to intragranular cracks,and to a transgranular crack network.Thermally induced damages reduce the dynamic peak splitting strength and the maximum absorbed energy while increasing the peak radial strain.The fracture mode of the thermally damaged granite under dynamic loads is mode Ⅱ splitting failure.By using the axial roughness index Z2 a,the distribution ranges of the wedge‐shaped failure zones and the tensile failure zones in the fracture surfaces under dynamic Brazilian splitting can be effectively identified.The radial roughness index Z_(2)^(r)is sensitive to the strain rate and temperature.It shows a linear correlation with the peak splitting strength and the maximum absorbed energy and a linear negative correlation with the peak radial strain.Z_(2)^(r)can be used to quantitatively estimate the dynamic parameters based on the models proposed.

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

Precipitates Generation Mechanism and Surface Quality Improvement for Aluminum Alloy 6061 in Diamond Cutting

To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the precipitates generation of Al6061 on surface integrity and surface roughness.Based on the Johnson-Mehl-Avrami solid phase transformation kinetics equation, theoretical and experimental studies were conducted to build the relationship between the aging condition and the type, size and number of the precipitates for Al6061. Diamond cutting experiments were conducted to machine Al6061 samples under different aging conditions. The experimental results show that, the protruding on the chip surface is mainly Mg_(2)Si and the scratches on the machined surface mostly come from the iron-containing phase(α-, β-AlFeSi).Moreover, the generated Mg_(2)Si and α-, β-AlFeSi affect the surface integrity and the diamond turned surface roughness. Especially, the achieved surface roughness in SPDT is consistent with the variation of the number of AlFeSi and Mg_(2)Si with the medium size(more than 1 μm and less than 2 μm) in Al6061.

Effects of H_2O_2 pretreatment on surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy

The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectra,Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF)soaking test.It is found that the H2O2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni2O3,Na2TiO3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment.As a result,the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na+ ions from Na2TiO3 phase with H3O+ ions in SBF,which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H2O2 pretreatment.

The effect of heat treatment on the structure and morphology of poly （p-phenylene benzobisoxazole） fiber

The effect of heat treatment on the structure of Poly（p-phenylene benzobisoxazole） （PBO） fiber was studied by wide angle X-ray diffraction （WAXD） and differential scanning calorimetry-（DSC）, which resuits in confirmation of secondary crystallization in the heat treatment process. The effect of heat treatment on the structure and morphology of PBO fiber＇ s surface was investigated with X-ray photoelectron spectroscopic analysis （XPS）, scanning electron microscopy （SEM） and atomic force microscopy （AFM）. The results show that heat treatment not only has an effect on the composition of PBO fiber＇s surface, but also improves the microstmcture of PBO fiber, makes fiber more regular.

Effects of Steam Heat Treatment on the Surface Contact Angle of Chinese Fir

The aim of this study was investigate the effects of heat treatment on the contact angle of Chinese fir, and the indicators affecting the change of contact an-gle change. It was determined that the duration of treatment had significant effect on the change curves of contact angle of Chinese fir wood due to the change curves of contact angle became more centralized and orderly after the specimens heat treated at 180 ℃. Compared with the untreated wood, the contact angle in-creased from 51＆#176; to 124＆#176; after 4 h treatment, and hydroxyl absorbance of hy-drophilic functional groups decreased from 2.08 to 1.63, while carbonyl absorbance from 0.92 to 0.62. The surface roughness has not significant influence on the con-tact angle. Heat treatment of the Chinese fir caused surface morphological change, which produced hol owed-out phenomenon. The increased surface contact angle caused by heat treatment can be used for outdoor and sauna facilities.

The effect of sand-blasting and hydrofluoric acid etching on Ti CP2 and Ti CP4 surface topography

Titanium is widely used in biomedical applications from many years for its interesting properties, nevertheless there are a large number of researchers studying the way to improve the performances of biomedical devices. A large number of papers concern the study of “commercially pure titanium” (Ti CP) but, very often, no details are indicated regarding: 1) the type of Ti CP used;2) the sandblasting process;and 3) the analytic evaluation of surface topography. In this paper, the effect of sandblasting duration (1, 2, 4, 8 min) and hydrofluoric acid (HF) etching, as well as their combined or synergic effect, on the surface topography of CP grade 2 and grade 4, have been investigated. Results obtained show that sandblasting treatment duration should be different for Ti CP grade 2 and Ti CP grade 4 to achieve similar topography. The shape of the surface is highly modified after acid etching. The latter produces “peaks” when applied to not sand- blasted coupons, whilst cuts the “top of the peaks” in the sandblasted samples. Further we confirm that, the roughness parameter Ra (or Sa), is not sufficient to describe “the surface status” and we propose to use additional para- meters like: Sq, Sku and Ssk, to unequivocally describe surface topography of implants as well as well defined test procedures.

Non-Thermal Atmospheric Plasma:Can it Be Taken as a Common Solution for the Surface Treatment of Dental Materials?

This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs of titanium（Ti）（n：40）,cobalt chromium（Co-Cr）（n：40）,yttrium stabilized tetragonal zirconia polycrystals（Y-TZP）（n：40）and polymethylmethacrylate（PMMA）（n：40）materials were machined and smoothed with silicon carbide papers.The surface roughness was evaluated in a control group and in groups with different plasma exposure times [1-3-5 s].The average surface roughness（Ra）and contact angle（CA）measurements were recorded via an atomic force microscope（AFM）and tensiometer,respectively.Surface changes were examined with a scanning electron microscope（SEM）.Data were analyzed with two-way analysis of variance（ANOVA）and the Tukey HSD test α=0.05）.According to the results,the NTAP surface treatment significantly affected the roughness and wettability properties（P 〈 0.05）.SEM images reveal that more grooves were present in the NTAP groups.With an increase in the NTAP application time,an apparent increment was observed for Ra,except in the PMMA group,and a remarkable reduction in CA was observed in all groups.It is concluded that the NTAP technology could enhance the roughening and wetting performance of various dental materials.

Synergistic Effect of Atmospheric Pressure Plasma Pre-Treatment on Alkaline Etching of Polyethylene Terephthalate Fabrics and Films

Dyeing of PET materials by traditional methods presents several problems.Plasma technology has received enormous attention as a solution for the environmental problems related with textile surface modifications,and there has been a rapid development and commercialization of plasma technology over the past decade.In this work,the synergistic effect of atmospheric pressure plasma on alkaline etching and deep coloring of dyeing properties on polyethylene terephthalate（PET）fabrics and films was investigated.The topographical changes of the PET surface were investigated by atomic force microscopy（AFM）images,which revealed a smooth surface morphology of the untreated sample whereas a high surface roughness for the plasma and/or alkaline treated samples.The effects of atmospheric pressure plasma on alkaline etching of the structure and properties of PET were investigated by means of differential scanning calorimetry（DSC）,the main objective of performing DSC was to investigate the effect of the plasma pre-treatment on the T_g and T_m.Using a tensile strength tester YG065 H and following a standard procedure the maximum force and elongation at maximum force of PET materials was investigated.Oxygen and argon plasma pre-treatment was found to increase the PET fabric weight loss rate.The color strength of PET fabrics was increased by various plasma pre-treatment times.The penetration of plasma and alkaline reactive species deep into the PET structure results in better dyeability and leaves a significant effect on the K/S values of the plasma pre-treated PET.It indicated that plasma pre-treatment has a great synergistic effect with the alkaline treatment of PET.

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.

Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hi- erarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching （EE）. MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched （SEA） as well as Machined （M） surfaces respectively. The results show signifi- cant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

EFFECT OF N^+ ION IMPLANTATION ON SURFACE ROUGHNESS OF 40Cr STEEL

The different change tendencies of 2-and 3-dimensional surface roughnesses of 40Cr steel aremeasured and analysed.In 2-dimensional parameters,the data are measured amplitude parametersRa ,Rq ,Rpn,spacing parameters Sm,S,q and shape parameters Δq,Tp %,Rsk,Rku..In3-dimensional parameters,the similar amplitude and shape parameters are measured.The au-thors found that ion implantation lcads to reduction of the values of the amplitude parameters ofthe surface roughness remarkably.The values of the spacing parameters have no regular changes.The changes of surface profiles before and after ion implantations have been measured in detail.Inaddition,the auto-correlation function and the power spectrum are analysed for the surfaces ofdifferent implanting parameters.It is concluded that in the observed frequency range,the intensi-ties of various frequencies decrease widely and the coefficients of the auto-correlation of surfacesdecrease after ion implantation.

THE SCROOPING TREATMENT OF POLYESTER SILKLIKE FIBERS

In this paper the mechanism producing scrooping sound has been discussedtheoretically.It has been recognized that the continuous stick-slip vibrationhaving a certain period and the bigger △E(△E——enery released by stick-slipvibration at one time)are the requisite and surfficient conditions producingscrooping sound.For fiber sample,its surface properties and internal structureare two principal factors influencing scrooping sound. Considering the surface properties of polyester fiber after scrooping treatmentare the synthetic reflection of the properties used treatment reagents and thesurface properties of the fiber,how selecting proper reagents for scroopingtreatment would be the key factor influencing the scrooping effect.Sometreatment solutions having better scrooping effect have been obtained in the paper. In order to cause better scrooping effect,not only the treatment reagent andsurface properties of the fiber,but also the internal structure of the fiber must beconsidered,It has been shown in

纤维缠绕塑料内胆表面处理装置的设计与分析

为提高目前塑料内胆的表面处理质量以及处理时间,节约时间和人工成本,本文针对纤维缠绕塑料内胆的表面处理设计了一套自动化的处理装置。它主要可以实现塑料内胆的自动夹持夹紧定位以及塑料内胆表面处理等功能。文中主要介绍了所设计的夹持传动装置以及等离子表面处理装置等相关结构,并在SolidWorks软件中对此套装置进行了总体设计与装配,在Workbench中对部分零部件进行了强度校核,分析Workbench中的相关结果。结果显示,该装置达到了相关力学要求且能够平稳传动,满足设计要求。

Microstructure and surface of 2A12 aluminum alloy cladded with pure aluminum after solution treatment

The effects of solution temperature and holding time on the microstructure, mechanical properties and surface morphology of 2 A12 aluminum alloy sheets were discussed in this paper. The universal tensile tester was used to test the tensile strength and yield strength of aluminum alloy sheets with different treatment systems. The surface morphology of the alloy sheets was characterized by a white light interference profile scanner, and the microstructure of the sheets was characterized by optical microscope(OM), scanning electron microscope(SEM)and electron backscattered diffraction(EBSD). The results showed that the mechanical properties of the sheets could not satisfy GBT228.1-2010 national standard when the holding time was 10 min and the holding temperature was475 ℃. However, under the other heat treatment systems,the alloy could reach the GBT228.1-2010 national standard. Moreover, with the extension of the holding time, the part of the matrix gradually diffused into the aluminumclad layer. When the holding time was shorter than 25 min,the boundary between the matrix and the aluminum-clad layer was relatively obvious. And the diffusion gradually became obvious when the holding time was over 25 min.Thereby, the boundary became blurry. The further investigation suggested that the solution temperature of495 ℃ and the holding time of 35 min showed better mechanical properties and better surface morphology.

聚磷酸铵阻燃剂改性及应用研究进展

高分子量Ⅰ型聚磷酸铵是一种磷氮含量非常高的膨胀性阻燃剂,比卤系和有机磷系阻燃剂更加低碳环保。本文对聚磷酸铵改性阻燃剂的国内外研究现状、市场现状、国内的行业政策及规范进行了详细地分析,并对聚磷酸铵阻燃剂行业未来的发展趋势进行了预测。本文为我国聚磷酸铵阻燃剂行业企业的发展策略制定及技术升级改造提供了借鉴,同时也为我国阻燃剂行业的健康发展指明了方向。

砂光处理对翅荚木表面特性影响研究

以17年生翅荚木人工林木材为研究对象,对不同粒度砂光与涂饰处理前后的木材材色、表面粗糙度、表面润湿性及表面光泽度进行测定分析。结果表明:翅荚木人工林木材属于高明度、浅红色、高饱和度的黄色调为主的木材,不同粒度砂光处理对涂饰处理前后翅荚木人工林木材各色度学指标的影响均很小。砂光处理砂纸粒度从120目增至240目,翅荚木人工林木材表面Ra、Rz和Rsm随着砂纸粒度的增大均显著减小,而砂纸粒度从240目增至400目,Ra、Rz和Rsm随着砂纸粒度的增大变化均很小。翅荚木人工林木材表面自由能和润湿性随砂纸粒度的增大而增大。涂饰处理后,翅荚木人工林木材表面光泽度明显增大,经醇酸清漆和聚氨酯清漆涂饰处理后,表面光泽度分别在砂纸粒度为320目、400目时增幅最大。

阴极钛材表面处理工艺对其表面状态及铜离子电沉积初期行为的影响

目的研究表面处理工艺对钛材表面状态的影响,进一步探究阴极钛材表面状态对铜离子电沉积初期形核行为的影响。方法利用砂纸研磨、机械/电解抛光、化学腐蚀等不同的表面处理工艺,制备出不同表面状态的钛材,对钛材的表面粗糙度和形貌分别进行测试和扫描电镜观察。以不同表面状态的钛材作为阴极,进行铜离子的电沉积实验,对初始沉积层组织进行扫描电镜观察,并统计铜晶核的尺寸、覆盖率。结果砂纸研磨的钛材表面粗糙度最大,随着砂纸目数的增加,粗糙度降低,划痕变得细密,沉积的铜晶核尺寸较小、分布均匀、面覆盖率较高;抛光可显著降低钛材表面粗糙度,电解抛光的粗糙度最低,但铜晶核难以牢固附着;化学腐蚀会在钛材表面残留金属颗粒或暴露晶界组织,沉积的铜晶核分布不均匀且易发生团簇。结论铜离子的初始沉积形核行为与阴极钛材的表面粗糙度和缺陷状态密切相关,采用3000#~4000#砂纸精细研磨的方式,可使钛材表面粗糙度Rz保持在1~1.2μm,且表面覆盖有高密度均匀细小的划痕缺陷,最有利于铜离子的高密度均匀形核。

反向处理铜箔微纳组织形成机理及其对力学性能的作用机制

目的第五代移动通信技术(5G)时代,高频高速信号传输过程中由于“趋肤效应”引起的信号损耗甚至“失真”越来越严重,为了解决这一问题,提出了一种反向处理铜箔的新技术,然而国内当前应用的高性能反向处理铜箔(RTF)主要依赖进口,要想在短时间内缩小国内外铜箔性能和生产效率的差距,最终实现这类高端铜箔的国产化,必须在明确该类铜箔微纳结构形成机理及其对性能影响的前提下,加快制备工艺的开发和优化。方法采用电镀法在阴极钛辊上沉积了电解生箔,在其光面进行粗化和镀Zn层等后续处理获得反向处理铜箔,同时以国外反向处理铜箔为参照,采用X射线衍射仪、扫描电子显微镜和透射电子显微镜详细分析其微纳组织与结构,采用激光共聚焦显微镜和万能试验机测量其粗糙度和拉伸性能。结果本工作中的RTF具有与国外商业产品相似的微观结构,由小的等轴晶和较大的柱状晶组成,且包含较多的纳米孪晶,孪晶界占比为30.8%,平均宽度为7.9 nm。S面是均匀的米粒状铜颗粒,而M面是较大的圆锥形铜颗粒。S面上的Zn层均匀致密,厚度约为6.5 nm,只有小部分Zn扩散到基底上形成CuZn3相。但从S面到M面,优选取向从(111)Cu逐渐变为(220)Cu,这与参比RTF略有不同。性能方面,参比RTF的Ra和Rz分别为1.22、1.42μm,抗拉强度为335.10 MPa,伸长率为15.5%,本工作中的RTF具有较低的粗糙度,Ra和Rz分别为0.68、1.03μm,其强度也具有明显优势(393.68 MPa),但延展性低于参比样品。通过对比分析,总结了铜箔在初始外延、过渡生长和电沉积条件控制的生长阶段3个阶段的生长特性,给出了影响每个阶段晶粒生长的主要因素,并且详细讨论了晶粒尺寸和纳米孪晶宽度对铜箔拉伸性能的影响。结论对RTF微观结构和性能的深入研究,有助于找到高性能铜箔国产化“瓶颈”的根源,为高性能铜箔在5G通信领域的进一步发展和应用奠定基础。

金属-聚合物表面微纳形态的构筑与研究

界面结合强度一直是限制金属-聚合物异质构件发展的重要因素之一。在金属表面构筑微纳结构有利于改善界面物理、化学性能,提高金属-聚合物界面的结合强度。本文以金属表面处理工艺为切入点,综述了异质界面结合机理以及不同的表面处理工艺对界面结合效果的影响。首先,介绍了具有表面微纳形态的金属与聚合物之间产生作用力的三种机理。其次,讨论了较为常用的表面处理工艺以及不同表面处理工艺对微纳结构形态与界面结合特性的影响。最后,总结和分析了现有金属表面微纳结构的制备方法,对金属-聚合物异质构件中的表面处理问题提出了新的展望。本文对金属表面结构和异质构件性能之间的关系进行了系统的阐述,可为新型金属-聚合物表面微纳形态的构筑与研究进展提供理论依据。