A review on developing high-performance ZE41 magnesium alloy by using bulk deformation and surface modification methods

Magnesium(Mg)alloys are generally used in light-weight structural applications due to their higher specific strength.However,the usage of these Mg alloys is limited due to their poor formability at room temperature,which is attributed to lower count of slip systems associated with the hcp crystal structure.To address these limitations,several new magnesium alloys and also many processing strategies have been developed and reported in the literature.ZE41 Mg is an alloy with significant quantities of zinc(Zn)and rare earth(RE)elements and has emerged as a promising material for aerospace,automotive,electronics,biomedical and many other industries.To make this alloy more competitive and viable,it should possess better mechanical and corrosion properties.Hence,the current paper reviews the effect of bulk mechanical processing on grain refinement,microstructural modification,and corresponding changes in the mechanical behaviour of ZE41Mg alloy.Further,the effect of various surface modification techniques on altering the surface microstructure and surface properties such as wear and corrosion are also briefly summarized and presented.This review also discusses the challenges and the future perspectives in developing high-performing ZE41 Mg alloys.

Etching characteristics and surface modification of InGaSnO thin films under Cl_(2)/Ar plasma

Indium gallium tin oxide(IGTO)thin films have the potential for high mobility and lowtemperature processing,which makes them suitable for applications such as display backplanes and high-voltage switching devices.However,very few studies have investigated the plasmaetching characteristics of IGTO and changes in its properties after etching.In this study,the etching characteristics of IGTO were investigated using Cl_(2)/Ar plasma,and changes in surface properties were analyzed.Results showed that the etch rate increased with an increase in the proportion of Cl_(2),with the highest etch rate observed at 69 nm min^(-1)in pure Cl_(2)plasma with a gas flow rate of 100 sccm.Furthermore,increased radio-frequency power caused a rise in the etch rate,while a process pressure of 15 m Torr was optimal.The primary etching mechanism for IGTO thin films under Cl_(2)plasma was a chemical reaction,and an increased work function indicated the occurrence of defects on the surface.In addition,the etching process reduced the surface roughness of Cl_(2)-containing plasma,whereas the etching process in pure Ar plasma increased surface roughness.This study contributes to a better understanding of the plasmaetching characteristics of IGTO and changes in its properties after etching,providing valuable insights for IGTO-based applications.

Surface Modification Process by Electrical Discharge Machining with Ti Powder Green Compact Electrode

This paper describes a new method of surface modification by Electrical Discharge Machining (EDM). By using ordinary EDM machine tool and kerosene fluid, a hard ceramic layer can be created on the workpiece surface with Ti or other compressed powder electrode in a certain condition. This new revolutionary method is called Electrical Discharge Coating (EDC). The process of EDC begins with electrode wear during EDM,then a kind of hard carbide is created through the thermal and chemical reaction between the worn electrode material and the carbon particle decomposed from kerosene fluid under high temperature. The carbide is piled up on a workpiece quickly and becomes a hard layer of ceramic about 20 μm in several minutes. This paper studies the principle and process of EDC systemically by using Ti powder green compact electrode. In order to obtain a layer of compact ceramic film, it is very important to select proper electric pulse parameters, such as pulse width, pulse interval, peak current. Meantime, the electrode materials and its forming mode will effect the machining surface quality greatly. This paper presents a series of experiment results to study the EDC process by adopt different technology parameters. Experiments and analyses show that a compact TiC ceramic layer can be created on the surface of metal workpiece. The hardness of ceramic layer is more 3 times higher than the base body, and the hardness changes gradiently from surface to base body. The method will have a great future because many materials can be easily added to the electrode and then be coated on the workpiece surface. Gearing the parameters ceramic can be created with different thickness. The switch between deposition and removal process is carried out easily by changing the polarity, thus the gear to the thickness and shape of the composite ceramic layer is carried out easily. This kind of composite ceramic layer will be used to deal with the surface of the cutting tools or molds possibly, in order to lengthen their life. It also can be found wide application in the fields of surface repairing and strengthening of the ship or aircraft.

Surface modification of calcium carbonate:A review of theories,methods and applications

Calcium carbonate,which is widely employed as a filler added into the polymer matrix,has large numbers of applications owing to the excellent properties such as low cost,non-toxicity,high natural reserves and biocompatibility.Nevertheless,in order to obtain the good filling effect,calcium carbonate needs to be surface modified by organic molecules so as to enhance the dispersion and compatibility within the composites.This review paper systematically introduces the theory,methods,and applications progress of calcium carbonate with surface modification.Additionally,the key factors that affect the properties of the composites as well as the current difficulties and challenges are highlighted.The current research progress and potential application prospects of calcium carbonate in the fields of plastics,rubber,paper,medicine and environmental protection are discussed as well.Generally,this review can provide valuable reference for the modification and comprehensive utilization of calcium carbonate.

Surface modification and functionalization by electrical discharge coating:a comprehensive review

Hard coatings are extensively required in industry for protecting mechanical/structural parts that withstand extremely high temperature,stress,chemical corrosion,and other hostile environments.Electrical discharge coating(EDC)is an emerging surface modification technology to produce such hard coatings by using electrical discharges to coat a layer of material on workpiece surface to modify and enhance the surface characteristics or create new surface functions.This paper presents a comprehensive overview of EDC technologies for various materials,and summarises the types and key parameters of EDC processes as well as the characteristics of resulting coatings.It provides a systematic summary of the fundamentals and key features of the EDC processes,as well as its applications and future trends.

Influence of stearic acid surface modification on flowability and agglomeration of battery grade Li_(2)CO_(3)powder

This work investigates the flow and agglomeration behaviors of battery grade Li_(2)CO_(3)powder and the influence of stearic acid surface modification.The degree of agglomeration is directly related to the uniformity of Li_(2)CO_(3)and its powder mixtures.According to the Chinese National Nonferrous Metal Industry Standard,battery grade Li_(2)CO_(3)powder has D50 equal to 3–8μm which belongs to a micron-sized superfine powder.Therefore,with the extension of storage time,the serious agglomeration phenomenon occurs due to the large specific surface area and rough and irregular powder particles.The Hausner ratio(HR)of the unmodified sample increases from 1.14 to 1.41,and the corresponding flowability is classified as good to poor.Instead,among samples with doping stearic acid,the optimum amount of it is 0.10 wt%which exhibits an extremely stable HR value from 1.14 to 1.16.Meanwhile,after 156 days,the repose angle(AR)obtained for samples without surface modification and using 0.10 wt%stearic acid are calculated to be 49°and 28°,respectively.Based on the values of HR and AR,the flowability of the unmodified sample is poor while the sample modified with 0.10 wt%of stearic acid still maintain excellent powder flow property.Moreover,The LiMn_(2)O_(4)cathode material synthesized from modified Li_(2)CO_(3)powder with a stearic acid content of 0.10 wt%exhibits good crystallinity and comparable electrochemical performance to that prepared by commercial Li_(2)CO_(3).These results indicate that stearic acid has the potential to be an ideal modifier for battery grade Li_(2)CO_(3)powder that needs to be kept for a long time.

Ion Beam Surface Modification of Y-TZP and Effects of Subsequent Annealing

Tetragonal zirconia polycrystals containing 3 mol% yttria (3Y-TZP), which show Superplasticity at high temperatures, were irradiated using 130 MeV Zr+" ions in the TANDEM accelerator facility at Tokai Research Establishment, JAERI. The irradiation induced atomic displacement damage was analyzed by TRIM code. Changes in the mechanical properties and fracture behavior caused by the ion irradiation and the effects of subsequent annealing were studied. The distribution of micro-indentation depth as a function of the indentation position from the irradiated surface to the specimen interior was also examined. The occurrence of compressive residual stresses and increases in hardness and fracture toughness were found in the as-irradiated surface region of the specimen. The subsequent annealing revealed that these quantities were decreased gradually with raising the annealing temperature. Probable causes of the generation of the residual stress and the changes in mechanical properties and fracture mode due to the irradiation are discussed.

Effects of surface modification by Ni, Ti and B on electrochemical properties of Mg_(1.8)Cu_(0.2)Ni hydrogen storage alloy

Amorphous alloy Mg1.8Cu0.2Ni was successfully prepared by mechanical alloying （MA） and a series of （n-x）Ni- x（Ti＋B） composites were synthesized by MA. The electrochemical properties of Mgl.8Cu0.2Ni coated by Ni, Ti and B were studied by cyclic charge-discharge, linear polarization curve, and hydrogen diffusion coefficient experiments. Experimental results indicate that Mg1.8Cu0.2Ni-[0.9Ni0.6（Ti＋B）] composite which was MA 30 h exhibited the best performance and its initial discharge capacity arrived to 714.1 mAh/g. After 30 cycles the discharge capacity was above 530 mAh/g, which was much higher than that of Mg1.8Cu0.2Ni. And after 100 cycles it holded still 442.1 mAh/g. On all accounts, after modification by Ni, Ti and B, the initial discharge capacity and high-rate discharge ability of the electrode were evidently increased. At the same time, the cycle performance was also improved significantly.

Study on the Effect of Surface Modification on the Properties of Bentonite Greases

In order to investigate the influening factors of organic modification procedure and find out connections between organic modification and the properties of bentonite greases, organic montmorillonite(OMMT) thickeners with different surfactant dosages and constituents were synthesized through intercalation reaction between sodium montmorillonite(NaM MT) and quaternary ammonium surfactants in aqueous solvents. The lubricating greases were prepared with the resulting organoclays, while the penetration and oil separation of lubricating greases were evaluated, respectively. The surface modification process of montmorillonite(MMT) was analyzed and the thickening mechanism of OMMT was discussed in this study. The experimental results showed that, with an increasing amount of surfactant, the basal spacing between the clay platelets was increasing and the structure of modifier molecules layer in the interlayer was changing from lateral bilayer to paraffin-type bilayer. The optimal properties of lubricating greases were achieved, when the structure of surfactant molecules loaded in the interlayer was the paraffin-type monolayer, which meant that the dosage of modifier was equal to 120—140 mmol/(100g). Meanwhile, it was found that the thickening performance, colloid stability, anti-wear and friction-reducing performance of lubricating greases were improved, when the surfactants were mixed with octadecyl trimethyl ammonium chloride(OTAC) and hexadecyl trimethyl ammonium chloride(HTAC). And the optimum mole ratio of two surfactants is was 1:1.

Effect of Na3AlF6 Addition and Surface Modification of SiCp on the Microstructure and Mechanical Properties of SiCp/Al Composites

Al-matrix composites reinforced with 56.5 vol% SiC were prepared by powder metallurgy with different amounts of additives and surface modifications of SiCp. The crystalline phase, morphology, elements on the surface of SiCp and the interface between SiCp and Al were characterized by XRD, SEM, EDS and EPMA. The results show that it is favorable for the reaction between TiO2-C on the surface of SiCp and Al at the SiCp-Al interface at 1 050 ℃. Besides, the process of Na3 AlF6 melting, dissolving and then contacting with Al2 O3 formed the NaF-AlF3-Al2 O3 system, which generated OAlF2-, promoting the dessolution of Al2 O3 film on the surface of Al powder. Na3 AlF6 meets the needs of chemical reaction in TiO2-C-Al system at the SiCpAl interface in the way of offering more molten Al. After 0.75 wt% Na3 AlF6 was added into raw materials, the whole TiO2-C film and most SiO2 film were destroyed and the interfacial bonding between SiCp and Al was keeping good, in which no obvious void and crack were observed. Meanwhile, no brittle Al4 C3 phase formed in the system. At this time, the flexure strength and density of samples presented optimal values, reaching up to 106.5 MPa and 90.77% respectively.

Mechano-activated surface modification of calcium carbonate in wet stirred mill and its properties

Surface modification of calcium carbonate particles using sodium stearate(SDS) as a modification agent incorporated with the simultaneous wet ultra-fine grinding in the laboratory stirred mill was investigated. The physical properties and application properties of modified calcium carbonate were measured and evaluated. The action mechanism between SDS and calcium carbonate in the modification was studied by infrared spectrometry(IR) and X-ray photoelectron energy spectroscopy(XPS). The results indicate that the crushing mechanic force intensity can obviously influence the modification effect of calcium carbonate because of mechano-chemical effect. The hydrophilic surface of calcium carbonate is turned into hydrophobic after modification. The properties of polyethylene(PE) filled by modified calcium carbonate powder is markedly improved. And the adsorption of SDS could occur by chemical reaction with calcium carbonate surface.

Organic Surface Modification and Characterization of Anatase Titanium Dioxide

For the purpose of increasing the dispersion of anatase titanium dioxide(A-TiO2)in organic matrix, the surface organic modification of A-TiO2 with the modifier of sodium stearate and sodium oleate, respectively, was studied. The process condition of modification was optimized, the performance of modified A-TiO2 was characterized and the mechanism between modifier and A-TiO2 was analyzed. The main contents and results are as

Influence of surface modification of SrFe12O19 particles with oleic acid on magnetic microsphere preparation

Oleic acid was used as surface modification agent to improve the hydrophobicity of magnetic strontium hexaferrite particles. The structure and properties of treated magnetic particles were characterized by scanning electronic microscopy （SEM）, Fourier transform infrared spectra （FTIR）, powder X-ray diffraction （XRD） and magnetic property measurement system （MPMS）. The results show that oleic acid is chemically enwrapped on the surface of SrFe12O19 particles. Magnetic particles modified by oleic acid are highly dispersible and strongly responsive to magnetism but with slight decrease in saturated magnetization. The affinity between magnetic particles and monomers is improved by surface modification, resulting in increased particle incorporation in magnetic polymeric microspheres. The surface modification mechanism of magnetic particles by oleic acid is addressed in this work.

Microstructure and mechanical properties of CoCrFeMnNi high entropy alloy with ultrasonic nanocrystal surface modification process

In this study, mechanical properties improvement of equiatomic CoCrFeMnNi treated with an ultrasonic nanocrystal surface modification(UNSM) was studied. The applied UNSM treatment with static loads of 10 N, 20 N, and 60 N provided a severe plastic deformation, which produced a gradient structure. The nearsurface area exhibited a high number of dislocation densities and deformation twin interaction, leading to a surface strengthening and hardness improvement of up to 112% than the deformation-free interior region. Increment of dislocation densities and deformation twin formation on the surface also enhanced the yield and ultimate tensile strength of the UNSM-treated specimens. Furthermore, the combination of hard nanocrystallites layer on the surface and ductile coarse grain in the specimen interior as a result of the UNSM treatment successfully maintained the strength–ductility balance of the CoCrFeMnNi.

A new guide for improving mechanical properties of non-equiatomic FeCoCrMnNi medium-and high-entropy alloys with ultrasonic nanocrystal surface modification process

Ultrasonic nanocrystal surface modification (UNSM) treatment on non-equiatomic medium-and highentropy alloy (HEA) of Fex(CoCrMnNi)100-xis firstly introduced and its impact on microstructure and mechanical properties are revealed.By UNSM,severe plastic deformation-induced dislocation and deformation twins (DTs) arise at the topmost surface.Especially,Fe60(CoCrMnNi)40(Fe60),which is classified as a medium-entropy alloy (MEA),exhibits ε-martensitic transformation.In the room temperature tensile test,a high strength of ~600 MPa and ductility of ~65%elongation (strain to failure) is accomplished in Fe60.Initially formed DTs and ε-martensitic transformation by UNSM treatment plays a key role in retardation of necking point via both twinning-induced plasticity and transformation-induced plasticity.However,Fe20(CoCrMnNi)80(Fe20) comparatively shows low strength of ~550 MPa and ~40% elongation,owing to the low accommodation of DTs than Fe60.Our research will provide new guidelines for enhancing the mechanical properties of MEA and HEA.

Study on Modification of Waste Rubber Powder in Cement-Based Composites Mixed with Waste Rubber Powder

In view of the disadvantage that the mechanical properties of cement-based composites can be significantly reduced by incorporating waste rubber powder in situ, the surface modification methods of the original rubber powder by coupling agent KH560, sodium hydroxide, polyvinyl alcohol (PVA), methyl hydroxyethyl cellulose ether (MHEC) and tetraethyl orthosilicate (TEOS) as precursors were adopted respectively. The modification of waste rubber powder was studied by Change rate of mortar strength of cement-based composite mortar mixed with waste rubber powder. The results show that the hybrid modification method using tetraethyl orthosilicate as precursor has better ef-fect. When 5 phr ethyl orthosilicate is added, the compressive strength and flexural strength of cement-based composite mortar can be increased by 31.7% and 28%. Scanning electron microscopy (SEM) results show that the surface of waste rubber powder with good modification effect has many pro-trusions and flake-like porous structures which are beneficial to its bonding with cement-based materials.

Chemical Modification on Woven Jute and Nonwoven Wet-Laid Glass Fiber Sheet Reinforced Poly-(<i>ε</i>-Caprolactone) Composites

High-moisture regains nature of cellulosic fibers considered one of the critical drawbacks for jute-based applications. To minimize this by developing better interfacial adhesion, a hydrophobic nonwoven wet-laid glass fiber sheet used the woven jute fabric in this experiment. For this purpose, woven jute fabric was categorized into untreated, silane, alkali, and alkali-silane combined treatment then compounded with the solution of polycaprolactone (PCL). Fabrication of composites performed the following sandwich method based on different hot-pressing time with temperature for detecting a prominent fabrication parameter. Surface treated jute fibers characterized using FTIR spectroscopy. Hence, the mechanical and thermal properties of composites were investigated to find the consequence of chemical treatments into woven jute fabric. Alkali-silane combined chemical treatments resulting in improved 48.38% of tensile strength over untreated optimized composites. Scanning electron microscope (SEM) used for displaying interfacial adhesion between fiber and polymer matrix. Besides, further investigation demonstrated due to the combined chemical treatment of alkali-silane optimized composites significantly enhanced the thermogravimetric (TGA) stability in contrast to other composites.

氮化硅粉改性及其陶瓷高温摩擦磨损性能研究

以商用氮化硅粉体为研究对象,重点考察了粉体种类、粒度、杂质离子含量、相组成对所制材料性能的作用规律。该研究探讨了不同粉体对氮化硅陶瓷密度、抗弯强度、导热系数、摩擦磨损性能和微观形貌的影响。结果表明:采用甲醇改性液处理20 min得到的氮化硅粉体,制备得到了热力学性能最佳的氮化硅陶瓷:密度为3.16 g·cm^(-3)、抗弯强度为(727±20) MPa、热导率为71.6 W·m^(-1)·K^(-1)、Si_(3)N_(4)陶瓷与C/SiC陶瓷在1200℃下摩擦系数低于0.7,高温下氮化硅陶瓷仍表现出优异的耐摩擦磨损性能。

钛合金表面超疏水膜的制备及其耐蚀性与机械稳定性

采用阳极氧化工艺在Ti6A14V钛合金表面制备阳极氧化膜作为过渡层,然后喷涂SiO_(2)颗粒溶胶烘烤使其固化成膜,再通过正辛基三乙氧基硅烷表面修饰,制备出具有微纳米表面结构、接触角为151.6°的超疏水膜。结果表明:超疏水膜的主要成分为Ti、O、Si和C元素,腐蚀电流密度仅为8.06×10^(-8)A/cm^(2),较裸钛合金降低约一个数量级,并且电荷转移电阻和低频阻抗模值较裸钛合金分别增大约7000Ω·cm^(2)、3000Ω·cm^(2),表现出良好的耐蚀性,可作为耐腐蚀膜层对钛合金起到防护作用。超疏水膜经受80次落砂冲击、50次胶带剥离以及沿砂纸往复摩擦400 cm后,接触角仍然大于150°,保持超疏水状态。蜂窝状多孔结构的阳极氧化膜充当过渡层,使溶胶膜和表面修饰形成的薄膜与钛合金基体牢固结合,从而表现出良好的机械稳定性。

改性芳纶短纤维增强氯丁橡胶/顺丁橡胶复合材料的实验研究

采用等离子体/油酸钾协同处理对芳纶纤维进行改性,并研究了改性芳纶纤维对氯丁橡胶/顺丁橡胶并用胶的增强作用。结果表明,等离子体的高能冲击使芳纶纤维的表面粗糙度增大,增加了芳纶纤维的表面积,并在芳纶纤维表面引入活性位点;油酸钾改性促进了芳纶纤维极性的削弱及其与橡胶的界面结合;经过等离子体/油酸钾协同处理的改性芳纶纤维增强后,橡胶复合材料的拉伸强度提高了25.85%,定伸模量提高了34.65%,刚度提高了10.96%,在正硫化时间(t90)未改变的情况下,焦烧时间(t10)下降。