Influence of Non-smooth Surface on Tribological Properties of Glass Fiber-epoxy Resin Composite Sliding against Stainless Steel under Natural Seawater Lubrication

With the development of bionics, the bionic non-smooth surfaces are introduced to the field of tribology. Although non-smooth surface has been studied widely, the studies of non-smooth surface under the natural seawater lubrication are still very fewer, especially experimental research. The influences of smooth and non-smooth surface on the frictional properties of the glass fiber-epoxy resin composite（GF/EPR） coupled with stainless steel 316 L are investigated under natural seawater lubrication in this paper. The tested non-smooth surfaces include the surfaces with semi-spherical pits, the conical pits, the cone-cylinder combined pits, the cylindrical pits and through holes. The friction and wear tests are performed using a ring-on-disc test rig under 60 N load and 1000 r/min rotational speed. The tests results show that GF/EPR with bionic non-smooth surface has quite lower friction coefficient and better wear resistance than GF/EPR with smooth surface without pits. The average friction coefficient of GF/EPR with semi-spherical pits is 0.088, which shows the largest reduction is approximately 63.18% of GF/EPR with smooth surface. In addition, the wear debris on the worn surfaces of GF/EPR are observed by a confocal scanning laser microscope. It is shown that the primary wear mechanism is the abrasive wear. The research results provide some design parameters for non-smooth surface, and the experiment results can serve as a beneficial supplement to non-smooth surface study.

Bonding characteristics of the Al_2O_3-metal composite coating fabricated onto carbon steel by combustion synthesis

The fabrication of an alumina-metal composite coating onto a carbon steel substrate by using a self-propagating high-temperature synthesis technique was demonstrated. The effects of the type and thickness of the pre-coated layer on the binding structure and surface qual- ity of the coating were systematically investigated. The macrostructure, phase composition, and bonding interface between the coating and the substrate were investigated by scanning electronic microscopy （SEM）, X-ray diffraction （XRD）, and energy-dispersive X-ray spectrometry （EDS）. The diffraction patterns indicated that the coating essentially consisted of α-Al2O3, Fe（Cr）, and FeO-Al2O3. With an increase in the thickness of the pre-coated working layer, the coating became more smooth and compact. The transition layer played an important role in enhancing the binding between the coating and the substmte. When the pre-coated working layer was 10 mm and the pre-coated transition layer was 1 ram, a compact structure and metallurgical bonding with the substrate were obtained. Thermal shock test results indicated that the ceramic coating exhibited good thermal shock resistance when the sample was rapidly quenched from 800℃ to room temperature by plunging into water.

TiC-Maraging stainless steel composite:microstructure, mechanical and wear properties

Particulate TiC reinforced 17-4PH and 465 maraging stainless steel matrix composites were processed by conventional powder metallurgy （P/M）. TiC-maraging stainless steel composites with theoretical density 〉97% were produced using conventional P/M. The microstructure, and mechanical and wear properties of the composites were evaluated. The microstructure of the composites consisted of （core-rim structure） spherical and semi-spherical TiC particles depending on the wettability of the matrix with TiC particles. In TiC-maraging stainless steel composites, 465 stainless steel binder phase showed good wettability with TiC particles. Some microcracks appeared in the composites, indicating the presence of tensile stresses in the composites produced during sintering. The typical properties, hardness, and bend strength were reported for the composites. After heat treatment and aging, an increase in hardness was observed. The increase in hardness was at- tributed to the aging reaction in maraging stainless steel. The specific wear behavior of the composites strongly depends on the content of TiC particles and their interparticle spacing, and on the heat treatment of the maraging stainless steel.

Synthesis of steel slag ceramics: chemical composition and crystalline phases of raw materials

Two types of porcelain tiles with steel slag as the main raw material （steel slag ceramics） were synthesized based on the CaO-A1203-SiO2 and CaO--MgO-SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite, a-quartz, magnetite, and pyroxene crystals （augite and diopside） in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction （XRD） and electron probe X-ray microanalysis （EPMA） results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.

Beneficial use of stainless steel EAF slag as composite cement admixture and its heavy metals leaching risk analysis

This study analyzes the feasibility of using stainless steel electric arc furnace （EAF） slag as composite cement admixture and the risk of leaching-out of heavy metals. The results show that the stainless steel EAF slag, mainly made up of Ca2 SiO4, Ca3 Mg （ SiO4 ） 2, some Cr-containing minerals and in small particle size, is easily ground and has cementitious activity. EAF slag, when used as cement admixture, can be added with a maximum percentage of 32%. It can meet the strength requirements of the standard P · C 32.5 cement. When the mixing percentage is decreased to 25 % , the strength of the cement can be increased to that of P · C 42.5 cement. Other main quality indexes of composite cement, such as the setting time and stability, also satisfy standard requirements. The results also show that most of the heavy metals in the stainless steel EAF slag exist in a stable speciation. The concentration of heavy metals that leach out from the stainless steel EAF slag and the composite cement products is far lower than the standard limit of hazardous wastes. The main heavy metal, chromium, exists as less hazardous trivalent chromium. Therefore, the risk of heavy metals leaching out from the stainless steel EAF slag is low. The internal exposure index （IRa） and the external exposure index （Iγ） of the stainless steel EAF slag are both lower than 1.0, satisfying the standard requirements of the state for the radionuclides of building materials. Therefore, stainless steel EAF slag can be safely used as admixture to produce composite cement.

Structure and sliding wear behavior of 321 stainless steel/Al composite coating deposited by high velocity arc spraying technique

A typical 321 stainless steel/aluminum composite coating (321/Al coating) was prepared by high velocity arc spraying technique (HVAS) with 321 stainless steel wire as the anode and aluminum wire as the cathode. The traditional 321 stainless steel coating was also prepared for comparison. Tribological properties of the coatings were evaluated with the ring-block wear tester under different conditions. The structure and worn surface of the coatings were analyzed by scanning electron microscopy(SEM), X-ray diffractometry(XRD) and energy dispersion spectroscopy(EDS). The results show that, except for aluminum phase addition in the 321/Al coating, no other phases are created compared with the 321 coating. However, due to the addition of aluminum, the 321/Al coating forms a type of "ductile/hard phases inter-deposited" structure and performs quite different tribological behavior. Under the dry sliding condition, the anti-wear property of 321/Al coating is about 42% lower than that of 321 coating. But under the oil lubricated conditions with or without 32 h oil-dipping pretreatment, the anti-wear property of 321/Al coating is about 9% and 5% higher than that of 321 coating, respectively. The anti-wear mechanism of the composite coating is mainly relevant to the decrease of oxide impurities and the strengthening action resulted from the "ductile/hard phases inter-deposited" coating structure.

Self-transforming stainless-steel into the next generation anode material for lithium ion batteries

Here,an extremely cost-effective and simple method is proposed in order to morphologically selftransform stain less steel from a completely inactive material to a fully operati onal,nanowire-structured,3D anode material for lithium ion batteries.The reagentless process of a single heating step of the plain stainless steel in a partially reduci ng atmosphere,converts the stain less steel into an active anode via metal-selective oxidation,creating vast spinel-structured nanowires directly from the electrochemically in active surface.The simple process allows the complete utilizati on of the 3D mesh structure as the electrochemically-active spinel nanowires greatly enhance the active surface area.The novel material and architecture exhibits high capacities(-1000 mAh/g after-400 cycles),long cycle life(>1100 cycles)and fast rate performance(>2C).Simple modulation of the substrate can result in very high areal and volumetric capacities.Thus,areal capacities greater than 10 mAh/cm^(2) and volumetric capacities greater than 1400 mAh/cm^(3) can be achieved.Using the proposed method,the potential reduction in cost from the use of battery-grade graphite is at least an order of magnitude,with considerable better results achieved in terms of capacity and intrinsic structural benefits of the substrate,which include direct contact of the active material with the current collector,lack of delamination and binder-free performance.This work provides a new paradigm and a key step in the long route to replace the commercial graphite anode as the next-geneation anode material.

Investigation of Sintering Technology for Composite of Stainless Steel and Partially Stabilized Zirconia

The sintering technology for mixed powdered extrusion rods of different proportions of stainless steel to magnesia partially stabilized zirconia (PSZ) was investigated. The effects of some sintering parameters including holding time, atmosphere and protective gas pressure on shrinkage, relative density, microstructure, micro-Vickers hardness and compression strength of sintered samples were mainly researched. The experimental results are as follows: (1) The shrinkage and the relative density of the sintered samples decrease as increasing stainless steel content in the composite, except for the case containing 90 percent of stainless steel; (2) The porosity in PSZ matrix rises as increasing the stainless steel content in the composite; (3) Longer sintering holding time, higher sintering vacuum and gas-pressure sintering process not only enhance the relative density, but also improve microstructure of composite; (4) Micro-Vickers hardness of PSZ matrix decreases as increasing stainless steel content, while that of stainless steel particles in sintered samples varies unnoticeably.

Effect of Annealing on Fly-Line Microstructure and Properties of Explosively Composited Stainless Steel-Stainless Steel Plates

Effect of annealing on "fly-line"(adiabatic sheer line) microstructure and properties of explosively composited stainless steel-stainless steel plates was studied.Results show that the flyline microstructure will diminish through certain annealing process,while the cracks formed from fly-line microstructure will remain.Therefore,fly-line microstructure can be considered as a plastic deformation microstructure and crack source s meanwhile its formation is considered as a special plastic deformation mechanism of metal under explosive load.

CYCLIC OXIDATION OF Ni-La_2O_3 COMPOSITE COATINGS ELECTRODEPOSITED ON NICKEL AND Fe26Cr STAINLESS STEEL

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Oxidation Behavior of Fe26Cr1Mo Stainless Steel in the Presence of Ni-La_2O_3 Electrodeposited Composite Film

The oxidation behaviors of Fe26Cr1Mo with and without the Ni La 2O 3 electrodeposited composite film have been investigated by thermogravimetric analysis (TGA) and a scanning electron microscope equipped with an energy dispersive analytical X ray system(SEM/EDAX). The experimental results show that the oxide scale growing on Fe26Cr1Mo exposed at 900 ℃ spalled severely during cooling, while after the stainless steel was coated with the Ni La 2O 3 electrodeposited composite film, its high temperature cyclic oxidation resistance was significantly improved. The reason is that a La 2O 3 modified NiO scale, which has a superior adhesion to the substrate, was formed on the Fe26Cr1Mo stainless steel coated with Ni La 2O 3 composite film.

Effect of Electrode Materials on Electric Discharge Machining of 316 L and 17 - 4 PH Stainless Steels

Electric Discharge Machining (EDM) is one of the most efficiently employed non-traditional machining processes for cutting hard-to-cut materials, to geometrically complex shapes that are difficult to machine by conventional machines. In the present work, an experimental investigation has been carried out to study the effect of pulsed current on material removal rate, electrode wear, surface roughness and diameteral overcut in corrosion resistant stainless steels viz., 316 L and 17-4 PH. The materials used for the work were machined with different electrode materials such as copper, copper-tungsten and graphite. It is observed that the output parameters such as material removal rate, electrode wear and surface roughness of EDM increase with increase in pulsed current. The results reveal that high material removal rate have been achieved with copper electrode whereas copper-tungsten yielded lower electrode wear, smooth surface finish and good dimensional accuracy.

Influence of Tungsten and Cobalt Contents on the Microstructure Changes and Fracture Behavior of New Carbon-Free Steel-alloy Composites

The ever increasing demand for steel materials that have good combinations between strength and toughness urged all researchers working in the field of material science to find new alloys that can approach that requirement.Unfortunately strength and toughness of materials are always counter acting properties.However,carbon contents in the steel define to a great extent its strength and toughness.In this research an effort is paid to produce steel alloy composites that can give higher strength together with good toughness without alloying with carbon.The mechanism of strengthening in Iron-Cobalt-Tungsten composite alloys with variations in Co and W contents is investigated.The fracture toughness and hardness,are measured for all alloy composites under investigation.The changes in microstructures after heat treatment are emphasized using metallurgical microscopy and SEM-aided with EDX analyzing unit.

Microstructure and properties of composite of stainless steel and partially stabilized zirconia

To fabricate the metal-ceramics multi-layer hollow functionally gradient materials(FGMs) that might meet the requirement of repeated service and long working time of high temperature burners, such as spacecraft engine, the microstructure and properties of composite of stainless steel and partially stabilized zirconia were investigated. Samples of different proportions of stainless steel to partially yttria-stabilized zirconia were fabricated by powder extrusion and sintering method. Shrinkage, relative density, microstructure, micro-Vickers hardness, compression strength, bending strength, fractography morphology and electrical resistivity of sintered samples with different proportions of stainless steel were measured. The results show that threshold of metallic matrix composite(MMC) is approximately equal to 60%(volume fraction) stainless steel. The samples with 0 to 50%(volume fraction) stainless steel indicate ceramic brittleness and non-cutability, and the samples with 70% to 100%(volume fraction) stainless steel indicate metallic plasticity and cutability.

Experimental Study on Corrosion of Stainless Steel in Low Temperature Multi effect Seawater Desalination

Starting from the corrosion mechanism,this paper analyzes the characteristics of various types of stainless steel and selects the best performance composite plate composite plate stainless steel.Analyze and select the most suitable corrosion detection method based on specific practical multi working conditions,discuss the interference factors that affect metal corrosion during experimental simulation,and the advantages of newly developed sheet metal.The new development of composite board panels,with the substrate and composite materials applying their respective capabilities for MED,will bring breakthrough progress to the scientific research and engineering applica-tion of composite boards.

Thermodynamic analysis and formula optimization of steel slag-based ceramic materials by FACTsage software

Using steel slag as a main raw material of ceramics is considered as a high value-added way. However, the relationship among the initial composition, ceramic microstructure, and macroscopic properties requires further study. In this paper, a series of ceramics with different slag ratios （0-70wt%） were designed, and the software FACTsage was introduced to simulate the formation of crystalline phases. The simulation results indicate that mullite is generated but drastically reduced at the slag ratios of 0-25wt%, and anorthite is the dominant crystalline phase in the slag content of 25wt%-45wt%. When the slag ratio is above 45wt%, pyroxene is generated more than anorthite. This is because increasing magnesium can promote the formation of pyroxene. Then, the formula with a slag content of 40wt% was selected and optimized. X-ray diffraction results were good consistent with the simulation results. Finally, the water absorption and bending strength of optimized samples were measured.

INFLUENCE OF PHASE COMPOSITION ON PITTING CORROSION RESISTANCE OF SPUTTERED COATING OF 1Cr18Ni9Ti STAINLESS STEEL

A series of single bcc,bcc plus fcc duplex and single fcc microcrystalline coatings of 1Cr18Ni9Ti stainless steel were prepared by using sputtering technique.The resistance against pitting corrosion was studied by measurements of pitting corrosion potentials and electrochemical noise during initiation of corrosion pits.The results show that the sputtered coatings with single bcc phase or single fcc structure are more resistant to pitting corrosion than those with bcc plus fcc duplex phase structure.

Studies of diamond-like carbon (DLC) films deposited on stainless steel substrate with Si/SiC intermediate layers

In this work, diamond-like carbon （DLC） films were deposited on stainless steel substrates with Si/SiC intermediate layers by combining plasma enhanced sputtering physical vapour deposition （PEUMS-PVD） and microwave electron cyclotron resonance plasma enhanced chemical vapour deposition （MW-ECRPECVD） techniques. The influence of substrate negative self-bias voltage and Si target power on the structure and nano-mechanical behaviour of the DLC films were investigated by Raman spectroscopy, nano-indentation, and the film structural morphology by atomic force microscopy （AFM）. With the increase of deposition bias voltage, the G band shifted to higher wave-number and the integrated intensity ratio ID/IG increased. We considered these as evidences for the development of graphitization in the films. As the substrate negative self-bias voltage increased, particle bombardment function was enhanced and the sp^3-bond carbon density reducing, resulted in the peak values of hardness （H） and elastic modulus （E）. Silicon addition promoted the formation of sp^3 bonding and reduced the hardness. The incorporated Si atoms substituted sp^2- bond carbon atoms in ring structures, which promoted the formation of sp^3-bond. The structural transition from C-C to C-Si bonds resulted in relaxation of the residual stress which led to the decrease of internal stress and hardness. The results of AFM indicated that the films was dense and homogeneous, the roughness of the films was decreased due to the increase of substrate negative self-bias voltage and the Si target power.

Experimental investigation of erosion rate for gas-solid two-phase flow in 304 stainless/L245 carbon steel

Erosion is one of the most concerning issues in pipeline flow assurance for the Oil&Gas pipeline industries,which can easily lead to wall thinning,perforation leakage,and other crucial safety risks to the steady operation of pipelines.In this research,a novel experimental device is designed to investigate the erosion characteristics of 304 stainless and L245 carbon steel in the gas-solid two-phase flow.Regarding the impacts on erosion rate,the typical factors such as gas velocity,impact angle,erosion time,particle material and target material are individually observed and comprehensive analyzed with the assistance of apparent morphology characterized via Scanning Electron Microscope.Experimental results show that the severest erosion occurs when the angle reaches approximate 30°whether eroded by type I or type II particles,which is observed in both two types of steel.Concretely,304 stainless steel and L245 carbon steel appear to be cut at low angles,and impacted at high angles to form erosion pits.In the steady operational state,the erosion rate is insensitive to the short erosion time and free from the influences caused by the“erosion latent period”.Based on the comparison between experimental data and numerical results generated by existing erosion models,a modified model with low tolerance(<3%),high feasibility and strong consistency is proposed to make an accurate prediction of the erosion in terms of two types of steel under various industrial conditions.

Effect of stabilizing elements Nb and Ti on the microstructure and properties of low carbon ferritic stainless steel

The effect of stabilizing elements, such as Nb and Ti, on the microstructure and properties of low carbon ferritic stainless steel （FSS） has been investigated. The results of the Thermo-calc simulation have shown that the interstitial elements, such as C and N, may be completely stabilized by the addition of Nb and Ti. With the increase of Nb and Ti contents ,the α ＋ γ two phases gradually transfer to a single α-phase under a high temperature condition ,and the content of the carbide M23 C6 gradually decreases. The microstructure has indicated that the combined addition of Nb and Ti can promote the recrystallization of the band structure and form more uniform equiaxed grains. Also, with the increase of Nb and Ti contents,the elongation, the r-value and the corrosion resistance of cold-rolled and annealed sheets are improved prominently. In comparison with the effect of Ti ,the addition of Nb is more beneficial to the increase of r-value and the corrosion resistance.