Structure and wear resistance of TiN and TiAlN coatings on AZ91 alloy deposited by multi-arc ion plating

In order to investigate the microstructure of TiN and TiAlN coatings and their effect on the wear resistance of Mg alloy, TiN and TiAlN coatings were deposited on AZ91 magnesium alloy by multi-arc ion plating technology.TiN and Ti70Al30N coatings were prepared on the substrate,respectively,which exhibited dark golden color and compact microstructure.The microstructures of TiN and Ti70Al30N coatings were investigated by X-ray diffractometry(XRD)and scanning electron microscopy(SEM).The micro-hardness and wear resistance of TiN and Ti70Al30N coatings were investigated in comparison with the uncoated AZ91 alloy. The XRD peaks assigned to TiN and TiAlN phases are found.The hardness of TiN coatings is two times as high as that of AZ91 alloy, and Ti70Al30N coating exhibits the highest hardness.The wear resistance of the hard coatings increases obviously as result of their high hardness.

STUDY ON HIGH TEMPERATURE PERFORMANCES OF MCrAlX COATINGS DEPOSITED BY MULTI-ARC ION PLATING

NCoCrAlSiYHf and CoNiCrAlTaY coatings which belong to protective Al 2O 3 scale forming type were deposited by multi arc ion plating technique . The effect of deposition process parameters on qualities of the coatings was discussed. The high temperature oxidation performances isothermal oxidation with 950℃ / 500h and 1100℃ / 100h were studied. And also, the hot corrosion performances at 700℃ and 800℃, with molten mixed salt composed of 75%wt Na 2SO 4 and 25%wt NaCl were investigated. Then the high temperature protection decaying mechanisms were proposed.

Structure and Tribological Properties of CrTiAlN Coatings Deposited by Multi-Arc Ion Plating

CrTiAIN coatings were prepared by using a home-made industrial scale multi-arc ion plating system. The coatings were found to be composites of face-center-cubic CrN and TiN. The surface roughness, microhardness, and tribological properties of the films were significantly affected by the nitrogen pressure and dc-pulsed bias voltage applied to the substrate. The CrTiA1N coatings with the smoothest surfaces were obtained at optimum conditions of nitrogen pressure of 5.0 Pa and bias voltage of -200 V. The samples were found to exhibit a hardness of 2900 HV0.05 with an average friction coefficient of 0.16 and wear rate of 1.5× 10^-16 m^3/N.m against cemented carbide.

Microstructure and mechanical properties of TiN/TiAlN multilayer coatings deposited by arc ion plating with separate targets

TiN/TiAlN multilayer coatings were prepared by arc ion plating with separate targets. In order to decrease the unfavorable macroparticles, a straight magnetized filter was used for the low melting aluminium target. The results show that the output plasmas of titanium target without filter and aluminium target with filter reach the substrate with the same order of magnitude. Meanwhile, the number of macropartieles in TiN/TiAlN multilayer coatings deposited with separate targets is only 1/10-1/3 of that deposited with alloy target reported in literature. Al atom addition may lead to the decrease of peak at （200） lattice plane and strengthening of peak at （111） and （220） lattice planes. The measured hardness of TiN/TiAlN multilayer coatings accords with the mixture principle and the maximum hardness is HV2495. The adhesion strength reaches 75 N.

Corrosion behavior of micro-arc oxidation coating on AZ91D magnesium alloy in NaCl solutions with different concentrations

Ceramic oxide coatings were prepared on AZ91D magnesium alloys in alkaline silicate solution using micro-arc oxidation（MAO） technique.The corrosion behavior of MAO coating on AZ91D magnesium alloys in NaCl solutions with different concentrations（0.1%,0.5%,1.0%,3.5% and 5.0% in mass fraction） was evaluated by electrochemical measurements and immersion tests.The results showed that the corrosion rate of the MAO coated AZ91D increased with increasing chloride ion concentration.The main form of corrosion failure was localized corrosion for the MAO coated AZ91D immersed in higher concentration NaCl solutions（1.0%,3.5% and 5.0%）,while it was general corrosion in dilute NaCl solutions（0.1% and 0.5%）.Two different stages of the failure process of the MAO coated AZ91D could be identified：1） occurrence of the metastable pits and 2） growth of the pits.Different equivalent circuits were also proposed based on the results of electrochemical impedance spectroscopy（EIS） for the MAO coated AZ91D immersed in different concentrations of NaCl solutions for 120 h.

Effect of cerium ion(Ⅲ) on corrosion resistance of organic-inorganic hybrid coating on surface of aluminum-tube used in refrigeration equipment

Organic?inorganic hybrid coating on the surface of aluminum-tube used in refrigeration equipment using cerium ion (III) as the additive was fabricated by sol?gel method, and the structure of the coating was confirmed by FT-IR. The results of the characterization show that the corrosion resistance of the coating with 1.5 mmol/L cerium ion (III) gains significant improvement, in which the colour retention time of CuSO4 extends to 500 s, the anti-acid and alkali corrosion rates reduce by 67% and 70% compared with the blank one, respectively, and the salt spray tests also show good corrosion resistance. The electrochemical tests demonstrate that the self-corrosion current density and potential of the sample with hybrid coating are about 2.877×10?7 A/cm2 and?0.550 V, respectively. The metallographic and SEM images show that the hybrid coating is uniform and dense, and the EDS analysis confirms that the coating is mainly composed of Al, Si and Ce elements.

Synthesis and characterization of LiFePO_4 coating with aluminum doped zinc oxide

Aluminum doped zinc oxide （AZO）, as an electrically conductive material, was applied to coating on the surface of olivine-type LiFePO4 synthesized by solid-state method. The charge-discharge test results show that the rate performance and low-temperature performance of LiFePO4 are greatly improved by the surface treatment. Even at 20C rate, the discharge specific capacity of 100.9 mA.h/g was obtained by the AZO-coated LiFePO4 at room temperature. At -20 ℃, the discharge specific capacity at 0.2C for un-coated LiFePO4 and the coated one are 50.3 mA.h/g and 119.4 mA.h/g, respectively. It should be attributed to the electrically conductive AZO-coating which increases the electronic conductivity of LiFePO4. Furthermore, the surface-coating increases the tap-density of LiFePO4. The results indicate that the AZO-coated LiFePO4 is a good candidate of cathode material for applying in lithium power batteries.

Properties of TiAICrN coatings prepared by vacuum cathodic arc ion plating

TiAlCrN coatings were deposited by means of vacuum cathodic arc ion plating technique on TC 11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） titanium alloy substrates. The composition, phase structure, mechanical performance, and oxidation-resistance of the nivide coatings were investi- gated by scanning electron microscopy （SEM）, atomic force microscope （AFM）, X-ray diffraction （XRD）, auger electron spectroscopy （AES）, and X-ray photoelectron microscopy （XPS）. A new process for preparing protective coatings of the titanium alloy is successfully ac- quired. The experimental results indicate that the added element chromium in the TiAlN coatings make a contribution to form the （220） pre- ferred direction. The phases of the coatings are composed of （Ti,Al）N and （Ti,Cr）N. After 700~C and 800~C oxidation, AES analysis shows that the diffusion distribution of the TiAlCrN coatings emerges a step shape. From the outside to the inner, the concentrations of O, Al, and Cr reduce, but those of Ti and N increase. The Al-rich oxide is formed on the surface of the coatings, and the mixed structure of Ti-rich and Cr-rich oxides is formed in the internal layer. The oxidation resistance of the TiAlCrN coatings is excellent at the range of 700 to 800~C. Adhesion wear is the dominant mechanical characteristic for the titanium alloy at room temperature, and the protective coatings with high hardness can improve the mechanical properties of the titanium alloy. The wear resistance of the TC 11 alloy is considerably improved by the TiAlCrN coatings.

Effect of Rare Earth Element Cerium on Mechanical Properties and Morphology of TiN Coating Prepared by Arc Ion Plating

TiN coatings were deposited on polished substrates of W18Cr4V high speed steel by means of vacuum arc ion plating. The effect of cerium on adhesion between TiN coating and substrate was studied. The microstructures and composition of TiN coatings were also investigated by means of scanning electron microscope (SEM), Auger electron spectroscopy (AES), and X ray diffraction (XRD) technique. It was found that cerium is an effective modifying agent and the addition of suitable amount of cerium to TiN coatings can produce relatively excellent properties such as micro hardness, wear resistance, oxidation resistance and porosity. The experimental results show that the added cerium in TiN coatings makes a contribution to form the preferred direction along with a (111) or (222) close packed face, which may be one of the reasons that improves some properties mentioned above.

The Surface Coating of Commercial LiFePO_4 by Utilizing ZIF-8 for High Electrochemical Performance Lithium Ion Battery

The requirement of energy-storage equipment needs to develop the lithium ion battery(LIB) with high electrochemical performance. The surface modification of commercial LiFePO_4(LFP) by utilizing zeolitic imidazolate frameworks-8(ZIF-8) offers new possibilities for commercial LFP with high electrochemical performances.In this work, the carbonized ZIF-8(C_(ZIF-8)) was coated on the surface of LFP particles by the in situ growth and carbonization of ZIF-8. Transmission electron microscopy indicates that there is an approximate 10 nm coating layer with metal zinc and graphite-like carbon on the surface of LFP/C_(ZIF-8) sample. The N_2 adsorption and desorptionisotherm suggests that the coating layer has uniform and simple connecting mesopores. As cathode material, LFP/C_(ZIF-8) cathode-active material delivers a discharge specific capacity of 159.3 m Ah g^(-1) at 0.1 C and a discharge specific energy of 141.7 m Wh g^(-1) after 200 cycles at 5.0 C(the retention rate is approximate 99%). These results are attributed to the synergy improvement of the conductivity,the lithium ion diffusion coefficient, and the degree of freedom for volume change of LFP/C_(ZIF-8) cathode. This work will contribute to the improvement of the cathode materials of commercial LIB.

Effects of Yttrium Ion on Formation Mechanism of ZrO_2-Y_2O_3 Ceramic Coatings Formed by Plasma Electrolytic Oxidation on Al-12Si Alloy

ZrO2-Y2O3 ceramic coating was produced by plasma electrolytic oxidation （PEO） on ZAlSil2Cu3Ni2 alloy. The microstructure and phase composition of the coating were investigated by SEM and XRD.： The results show that adding an appropriate amount of yttrium ion can improve the growing rate of ceramic coating at different oxidation stages and decrease arc voltage. The thickness of ZrO2-Y2O3 coating is 16 μn thicker than that of ZrO2 coating and the maximum oxidation rate improves by 0.6 μm/min. In addition, the arc voltage decreases from 227 to 172 V. It can be seen that the rate of oxidation firstly increases to some extent and then decreases with the content of yttrium ion increasing. The growth rate reaches the maximum while the content of yttrium ion is 0.05 g-L-1The maximum thickness is 90 μm.Compared to ZrO2 coating, the micropores of ZrO2-Y2O3 coating are less and the ceramic layer is repeatedly deposited by ZrO2 and Y2O3 ceramic particles. Meanwhile, the binding force between coating and substrate is better and the coating is uniform and compact. The ceramic layer is mainly composed of c-Y0.15Zr0.85O1.93□0.07, m-ZrO2, α-Al2O3, ,γ-Al2O3 and Y2O3. It is indicated that ZrO2 has beert fully stabilized by yttrium ion through the formation of solid solution.

Ultrasonic characterization of modified Cr_2O_3 coatings by reflection coefficient spectroscopy

Pores,microcracks and density of plasma sprayed Cr2O3 coatings before and after high-intensity pulsed ion beam(HIPIB) irradiation were investigated using the ultrasonic reflection coefficient spectroscopy(URCS).The URCS was analyzed based on an acoustic transmission model for the multi-layered structure.The longitudinal velocity in the coatings was calculated from the experimental URCS,and the attenuation coefficient expression was deduced by comparing the experimental and numerical fitting amplitude spectral lines.The longitudinal velocity of as-sprayed Cr2O3 coating is 2 002 m/s,and increases to 2 099 and 2 148 m/s after being irradiated by HIPIB with 1 and 5 shots.Correspondingly,the factor A changes from 0.046 to 0.026 and 0.020 and n from 1.702 to 1.658 and 1.649 in the attenuation coefficient expression of α=Af n.It is observed that the surface morphology of Cr2O3 coatings changes from rough and porous to smooth and uniform with the increase of shot number,which accords with the ultrasonic analyses reasonably.The URCS seems to provide a convenient and nondestructive method to characterize surface modification of the plasma sprayed coatings.

Effect of cathode composition on microstructure and tribological properties of TiBN nanocomposite multilayer coating synthesized by plasma immersion ion implantation and deposition

Nanocomposite multilayer TiBN coatings were prepared on Si(100) and 9Cr18Mo substrates using TiBN composite cathode plasma immersion ion implantation and deposition technique(PIIID). Synthesis of TiBN composite cathodes was conducted by powder metallurgy technology and the content of hexagonal boron nitride(h-BN) was changed from 8% to 40%(mass fraction). The as-deposited coatings were characterized by energy dispersive spectrometer(EDS), grazing incidence X-ray diffraction(GIXRD), Fourier Transform Infrared Spectroscopy(FTIR) and high resolution transmission electron microcopy(HRTEM). EDS results show that the B content of the coatings was varied from 3.71% to 13.84%(molar fraction) when the composition of the h-BN in the composited cathodes was changed from 8 % to 40%(mass fraction). GIXRD results reveal that the TiBN coatings with a B content of 8% has the main diffraction peak of TiN(200),(220) and(311), and these peaks disappear when the B content is increased. FTIR analysis of the multilayer coatings showed the presence of h-BN in all coatings. TEM images reveal that all coatings have the characteristics of self-forming nanocomposite multilayers, where the nanocomposites are composed of face-centered cubic Ti N or h-BN nanocrystalline embedded in amorphous matrix. The tribological tests reveal that the Ti BN coatings exhibit a marked decrease of coefficient at room temperature(~0.25). The improved properties were found to be derived from the comprehensiveness of the self-forming multilayers structure and the h-BN solid lubrication effects in the coatings.

Tailoring Iron-Ion Release of Cellulose-Based Aerogel-Coated Iron Foam for Long-Term High-Power Microbial Fuel Cells

The presence of iron(Fe) has been found to favor power generation in microbial fuel cells(MFCs). To achieve long-term power production in MFCs, it is crucial to effectively tailor the release of Fe ions over extended operating periods. In this study, we developed a composite anode(A/IF) by coating iron foam with cellulose-based aerogel. The concentration of Fe ions in the anode solution of A/IF anode reaches 0.280 μg/mL(Fe^(2+) vs. Fe^(3+) = 61%:39%) after 720 h of aseptic primary cell operation. This value was significantly higher than that(0.198 μg/mL, Fe^(2+) vs. Fe^(3+) = 92%:8%) on uncoated iron foam(IF), indicating a continuous release of Fe ions over long-term operation. Notably, the resulting MFCs hybrid cell exhibited a 23% reduction in Fe ion concentration(compared to a 47% reduction for the IF anode) during the sixth testing cycle(600-720 h). It achieved a high-power density of 301 ± 55 mW/m^(2) at 720 h, which was 2.62 times higher than that of the IF anode during the same period. Furthermore, a sedimentary microbial fuel cell(SMFCs) was constructed in a marine environment, and the A/IF anode demonstrated a power density of 103 ± 3 mW/m^(2) at 3240 h, representing a 75% improvement over the IF anode. These findings elucidate the significant enhancement in long-term power production performance of MFCs achieved through effective tailoring of Fe ions release during operation.

Effect of N-ion implantation and diamond-like carbon coating on fretting wear behaviors of Ti6Al7Nb in artificial saliva

The tribology behaviors of Ti6Al7Nb,its alloy with N-ion implantation,and its alloy with diamond-like carbon(DLC)coating were investigated in artificial saliva.Fretting wear tests of untreated,N-ion implanted and DLC coated Ti6Al7Nb alloys plate against a Si3N4ball were carried out on a reciprocating sliding fretting wear test rig.Based on the analysis of X-ray diffraction,Raman spectroscopy,3-D profiler,SEM morphologies and frictional kinetics behavior analysis,the damage behavior of surface modification layer was discussed in detail.The results indicated that the fretting wear behavior of Ti6Al7Nb alloy with N-ion implantation was increased with the dose increase of the implanted nitrogen ions.Moreover,the DLC-coated Ti6Al7Nb alloy with low ion implantation could improve the fretting wear behavior greatly.In addition,the Ti6Al7Nb with DLC coating had better ncorrosion resistance due to the special compact structure.All results suggested that the Ti6Al7Nb with DLC coating had better wear resistance than that with N-ion implantation in artificial saliva.

EXPERIMENTAL STUDY ON SUPERFICIAL COAT OF GEARS OF NITRIDED 32Cr2MoV COATED WITH TiN FILM BY MULTI-ARC ION PLATING

After 32CrMoV is selected to manufacture nitrided gears coated with TiN by multi-arc ion plating, all of these uncoated gears and coated gears run in the gearbox under the same initial conditions so as to compare their difference concerning properties and microstructure. Experiment results indicate that tooth surface of the coated-TiN gears does not suffer surface abnormalities in meshed zone. Instead, the gears with nitrided case exhibit an abrasion mark on the meshed zone of tooth surface, which results in more weight loss of nitrided gears. The morphology of the surface suggests TiN film with more than 2 000 HV is so dense and smooth that coated-TiN gears have higher wear resistance compared with the uncoated gears. The microstructure of coated-TiN gears is finer, hardness is higher and its distribution of coated-TiN gears is more reliable than uncoated ones, which makes nitride layer combined with TiN film tightly. Consequently, the wear-resistance of gears has been dramatically promoted.

IMPROVEMENT OF ADHESION BETWEEN ION PLATED TiN COATING AND BASE METAL BY ADDING Y

The adhesion between the ion plated TiN coating and the base metal is improved by adding Y.The machenism of the effect of Y has been discussed as well.

Recent progress of surface coating on cathode materials for high-performance lithium-ion batteries

Lithium-ion batteries (LIB) have received substantial attention in the last 10 years,as they offer great promise as power sources that can lead to the electric vehicle (EV) revolution in the next 5 years.Since the cathode serves as a key component in LIB,its properties significantly affect the performance of the whole system.Recently,the cathode surface modification based on coating technique has been widely employed to enhance the electrochemical performances by improving the material conductivity,stabilising the physical structure of materials,as well as preventing the reactions between the electrode and electrolyte.In this work,we reviewed the present of a number of promising cathode materials for Li-ion batteries.After that,we summarized the very recent research progress focusing on the surface coating strategies,mainly including the coating materials,the coating technologies,as well as the corresponding working mechanisms for cathodes.At last,the challenges faced and future guidelines for optimizing cathode materials are discussed.In this study,we propose that the structure of cathode is a crucial factor during the selection of coating materials and technologies.

Friction and Wear Performances of Cathodic Arc Ion Plated TiAlSiN Coating under Oil Lubricated Condition

TiAlSiN coating was deposited on H13 hot work mould steel using cathodic arc ion plating（CAIP）. The surface-interface morphologies and phases of the obtained coating were analyzed using field emission scanning electron microscopy（FESEM） and X-ray diffraction（XRD）, respectively, and the morphologies, distributions of chemical elements and profiles of worn tracks were also researched using scanning electron microscopy（SEM）, energy disperse spectroscopy（EDS）, and optical microscope（OM）, respectively. The friction-wear performances of TiAlSiN coating under oil lubricated and dry fiction conditions were investigated, and the wear mechanisms of TiAlSiN coating were discussed. The experimental results show that the coating is primarily composed of（Ti, Al）N, AlTiN, and TiN hard phases, Si_3N_4 exists between the（Ti, Al）N crystal grains, increasing the coating microhardness to 3200 HV. The TiAlSiN coating has excellent performances of reducing friction and wear resistance, the average coefficient of friction（COF） of TiAlSiN coating under oil lubricated condition is only 0.05, lowered than the average COF of 0.211 under dry friction condition, the wear rate decreases by about 81.2% compared with that under dry friction condition. The wear mechanism of TiAlSiN coating under oil lubricated and dry friction conditions is composed of abrasive wear, fatigue wear, and abrasive wear, respectively. The internal friction of oil lubrication is a main factor of decreasing fatigue wear.

Effect of Organic Coating Corrosion Inhibitor on Protection of Reinforced Mortar

Corrosion of reinforced concrete is the most important cause of concrete structure deterioration. In the present study, the protective effect of the reinforcement mortars against corrosion is examined. In particular, the chloride penetration resistance on reinforced cement mortars using organic coating as additive containing was studied. The aforementioned additive consists of corrosion inhibitor for protection of steel rebars against pitting corrosion. For the experimental procedure, four (4) different types of reinforced mortars were prepared. The corrosion protection of the additive was evaluated by electrochemical methods, (linear polarization resistance, Half-cell Potential Resistance and Electrochemical Impedance Spectroscopy). In addition, the mass loss of steel rebars against time of partially immersed in NaCl solution was carried out in the lab. The experimental results showed that in all examined cases the organic coating provides anticorrosion protection on steel rebars against chlorides.