Regulating solid electrolyte interphase film on fluorinedoped hard carbon anode for sodium-ion battery

For the performance optimization strategies of hard carbon,heteroatom doping is an effective way to enhance the intrinsic transfer properties of sodium ions and electrons for accelerating the reaction kinetics.However,the previous work focuses mainly on the intrinsic physicochemical property changes of the material,but little attention has been paid to the resulting interfacial regulation of the electrode surface,namely the formation of solid electrolyte interphase(SEI)film.In this work,element F,which has the highest electronegativity,was chosen as the doping source to,more effectively,tune the electronic structure of the hard carbon.The effect of F-doping on the physicochemical properties of hard carbon was not only systematically analyzed but also investigated with spectroscopy,optics,and in situ characterization techniques to further verify that appropriate F-doping plays a positive role in constructing a homogenous and inorganic-rich SEI film.The experimentally demonstrated link between the electronic structure of the electrode and the SEI film properties can reframe the doping optimization strategy as well as provide a new idea for the design of electrode materials with low reduction kinetics to the electrolyte.As a result,the optimized sample with the appropriate F-doping content exhibits the best electrochemical performance with high capacity(434.53 mA h g^(-1)at 20mA g^(-1))and excellent rate capability(141 mAh g^(-1)at 400 mA g^(-1)).

The Hardness of Amorphous Si-DLC Films by Molecular Dynamics Simulations

Silicon-doped diamond-like carbon （Si-DLC） films possess the potential to improve wear performance of DLC films in humid atmospheres and at higher temperatures. But many experimental results of Si-DLC films show that their structure and mechanical properties have changed greatly with the increasing silicon content. Therefore, molecular dynamics （MD） simulations were used to generate hydrogen-free Si-DLC films and study their nano-indentation process under the interaction of a diamond indenter. The results show that sp3/sp2（C） （only carbon atoms） always decreases with the increasing silicon content. But sp3/sp2（C＋Si） ratio increases firstly and reaches a maximum at the silicon content of 0.2, and then decreases with the further increase of the silicon content. Bulk modulus and hardness of the Si-DLC films both decrease with the increasing of the silicon content, which has the same trend with Papakonstantinou and Ikeyama＇s results. It is concluded that the hardness of the Si-DLC films is dependent on sp3/sp2（C）, not sp3/sp2（C＋Si）.

INVESTIGATION ON DEPOSITIONS AND HARDNESS CHARACTERISTICS OF a-SiC:H FILMS

In this paper, a deposition feature of a SiC:H films deposited by a RF sputtering system and a effect on the hardness of the films with various deposition conditions are investigated, and the effects of the silicon on a C:H are studied. It follows from the results that the properties of hardness can be changed with the depositing conditions. An increase of silane in the gas phase allows to deposit a SiC:H having tetrahedral structure. The sets of deposition conditions by which the different types of a SiC:H films can be deposited are obtained.

Hardness Measurement and Evaluation of Double-layer Films on Material Surface

A method for hardness measurement and evaluation of double-layer thin films on the material surface is proposed. Firstly, it is studied how to obtain the force-indentation response with the finite element method when the indentation is less than 100 nanometers, in which current nanoindentation experiments have no reliable accuracy. The whole hardness-displacement curve and fitted equation are obtained. At last, a formula to predict the hardness of the thin film on the material surface is derived and favorably compared with experiments.

DEPOSITION OF TiBN HARD FILMS ON HOT-WORKING-STEEL DIES FOR ALUMINIUM EXTRUSION VIA A DUPLEX PROCESS

Hot working steels have been used as die materials for hot extrusion of aluminium. Due to tribological interaction at elevated temperature between the die bearing and the surface of extruded aluminium profiles, not only the surface quality of the extruded product, but also the lifetime of the dies decreases. Deposition of TiBN hard films on the die bearing could improve the die performance. Treatment should be done in a duplex process process combining a plasma nitriding pretreatment (PN) and a plasma assisted chemical vapour deposition (PACVD) of TiBN. In this study the influence of the process conditions on the properties of the duplex coatings was investigated. The relationship between structure and mechanical property was researched. For testing these TIBN hard films under elevated temperature conditions and for comparison with other possible coatings special extrusion dies with different coated bearings were used. The extrusion trials were performed on the 8MN-extrusion press at the research a nd development center for extrusion, Technical University of Berlin.

Evaluation of Interfacial Adhesion Property for Thin Hard Films with Fuzzy Method

According to nanoscratch results for the TiN film, an evaluation method for interfacial fracture toughness of thin hard films is presented with fuzzy concepts, which can account for such influential factors in scratch test as surface roughness and material imperfection. Based on configuration changes in scratching curves, the parameters RV and RF are defined as the relative ratios of tip vertical displacement and of friction coefficinet. Fuzzy features of the scratching curves are analyzed carefully. The critical load is deduced from fuzzy logic operations and used to calculate the value of interfacial fracture toughness. With this method, the interfacial fracture toughness of TiN/HSS is evaluated approximately as 4.18 MPam^1/2. Results show that the method is valid and can benefit the interfacial adhesion property investigation for thin hard films.

STUDY ON COMPOSITION, MICROSTRUCTURE AND HARDNESS OF DLC FILMS BY VCAD

DLC super-hard films have been deposited on the substrates of single crystalline Si, pure Ti and stainless steel 18-8 by a method of vacuum cathode arc deposition (VCAD). The composition, microstructure and micro-hardness of the films have been studied in this paper. The results indicate that hardness of the DLC films is different on the different substrates. Hardness of the films increases with decreasing in surface roughness of the films. The maximum value of micro-hardness belongs to the DLC films deposited under the hydrogen pressure of 0.35Pa and the negative bias of 100V.

Influence of oxidation heat on hard anodic film of aluminum alloy

The special experimental device and sulfuric acid electrolyte were adopted to study the influence of anodic oxidation heat on hard anodic film for 2024 aluminum alloy. Compared with the oxidation heat transferred to the electrolyte through anodic film, the heat transferred to the coolant through aluminum substrate is more beneficial to the growth of anodic film. The film forming speed, film thickness, density and hardness are significantly increased as the degree of undercooling of the coolant increases. The degree of undercooling of the coolant, which is necessary for the growth of anodic film, is related to the degree of undercooling of the electrolyte, thickness of aluminum substrate, thickness of anodic film, natural parameters of bubble covering and current density. The microstructure and performance of the oxidation film could be controlled by the temperature of the coolant.

Ti-Si-N films prepared by magnetron sputtering

A film growth mechanism, expressed in terms of depositing hard films onto the soft substrate, was proposed. Multicomponent thin films of Ti-Si-N were deposited onto Al substrate with a double-target magnetron sputtering system in an Ar-N 2 gas mixture. The Ti-Si-N films were investigated by characterization techniques such as X-ray diffraction (XRD), atomic force microscope (AFM), electron probe microanalyzer (EPMA), scratch test and nanoindentation. The as-deposited films have a good adhesion to Al substrate and appear with smooth and lustrous surface. The films show nanocomposite structure with nano TiN grains embedded in an amorphous SiN x matrix. The maximum hardness of the films was achieved as high as 27 GPa. The influences of the N 2 flow rate and substrate temperature on the growth rate and quality of the films were also discussed. For all samples, the Ar flow rate was maintained constant at 10 ml min 1 , while the flow rate of N 2 was varied to analyze the structural changes related to chemical composition and friction coefficient. The low temperature in the deposited Ti-Si-N films favors the formation of crystalline TiN, and it leads to a lower hardness at low N 2 flow rate. At the same time, the thin films deposited are all crystallized well and bonded firmly to Al substrate, with smooth and lustrous appearance and high hardness provided. The results indicate that magnetron sputtering is a promising method to deposit hard films onto soft substrate.

STRUCTURE AND BINDING STATE OF CN_x FILMS SYNTHESIZED BY FACING TARGETS SPUTTERING

CN x films were made by a facing targets sputtering ( FTS) systemon the Si(100) substrate under different N 2 partial pressure. XRD, XPS, FTIR and Raman Spectroscopy( RS) were measured to investigate the structure and the binding state of the film. The films are amorphous and the N/C increases with the N 2 partial pressure increasing and reaches 0 46 when the N 2 pressure is 100%. The N incorporated C forms N sp 2C and N sp 3C mainly and there is a small amount of C≡N.

Deposition of carbon nitride films for space application

Carbon nitride thin films were prepared by electron-beam evaporation assisted with nitrogen ion bombardment and TiN/CNx composite films were by unbalanced dc magnetron sputtering, respectively. It was found that the sputtered films were better than the evaporated films in hardness and adhesion. The experiments of atomic oxygen action, cold welding, friction and wearing were emphasized, and the results proved that the sputtered TiN/CNx composite films were suitable for space application.

Hardness Measurement and Evaluation of Thin Film on Material Surface

A method for hardness measurement and evaluation of thin films on the material surface was proposed. Firstly, it is studied how to obtain the force indentation response with a finite element method when the indentation is less than 100 nanometers, in which current nanoindentation experiments have not reliable accuracy. The whole hardness indentation curve and fitted equation were obtained. At last, a formula to predict the hardness of the thin film on the material surface was derived and favorably compared with experiments.

Preparation and characterization of thick cubic boron nitride films

Cubic boron nitride （c-BN） films are prepared by the radio frequency magnetron sputtering technique. The stresses and crystallinities of the films are estimated by the Fourier transform infrared spectroscopy of c-BN samples, including the peak shifts and varieties of full widths at half maximum. The effects of the B-C-N interlayer and the two-stage deposition method on the c-BN films are investigated. Then the thick and stable c-BN films are prepared by a combination of the two methods. The properties of the interlayer and film are also characterized.

Preparation and properties of organic-inorganic modified SiO_2 thin films

Polydimethylsiloxane （PDMS）, tetraethoxysilane （TEOS）, ethyl alcohol （EtOH） and deionized water were main raw materials to prepare silicone-modified hybrid thin films using sol-gel method. The effect of the contents of H2O and PDMS on thin films was studied. When the volume ratio of H20 to TEOS is 0.5, the optimum quality of thin films is obtained. And the gelation time is affected slightly by H20 content. Uniform thin films are obtained when the volume ratio of PDMS to TEOS is 0.2. Yet, the sol would be inactive in 6 d. Various properties of thin films were studied, including hardness, adhesive quality, hydrophobic property, corrosion protection property, and abrasion resistance. Test results show that the pencil hardness is generally 3-6 H, and adhesive quality achieves the highest standard of 0. When the sintering temperature is below 400℃, the contact angle is about 95° and hydrophobic films are obtained. The abrasion resistance of thin films is better than that of aluminum alloy when the sintering temperature is higher than 300℃. And the excellent corrosion protective effect is obtained by single-layer coating when the sintering temperature is higher than 400℃.

Effect of deposition parameters on mechanical properties of TiN films coated on 2A12 aluminum alloys by arc ion plating (AIP)

TiN films were deposited on 2A12 aluminum alloy by arc ion plating (AIP). The Vickers hardness of the films deposited at different bias voltages and different nitrogen gas pressures, and that of the substrate were measured. The surface roughness of the TiN films diposited at –30 V and –80 V respectively and at different nitrogen gas pressure was measured also. The mass loss of TiN films deposited at 0 V, –30 V and –80 V respectively were analyzed in dry sand rubber wheel abrasive wear tests and wet ones in comparison with uncoated Al alloy and austenitic stainless steel (AISI 316L). It is revealed that the highest hardness of the TiN film is obtained at a bias voltage of –30 V and a N2 gas pressure of 0.5 Pa. The surface roughness of the film is larger at –80 V than that at –30 V and reduces as the increase of the N2 gas pressure. The mass loss of TiN-film coated 2A12 aluminum alloy is remarkably less than that of uncoated Al alloy and also that of AISI 316L, which indicates that the abrasive wear rate is greatly reduced by the application of TiN coating. TiN coating deposited by arc ion plating (AIP) technique on aluminum alloy can be a potential coating for machine parts requiring preciseness and lightness.

Structure and oxidation resistance of W_(1-x)Al_xN composite films

A series of W1?xAlxN films(0<x<38.6%,mole fraction)were deposited by reactive magnetron sputtering.The composition,microstructure,mechanical properties and oxidation resistance of the films were characterized by EPMA,XRD,XPS,nano-indentation,SEM and HRTEM.The effect of Al content on the microstructure and oxidation resistance of W1?xAlxN films was investigated.The results show that WN film has a face-centered cubic structure.The preferred orientation changes from(111)to(200).The W1?xAlxN films consist of a mixture of face-centered cubic W(Al)N and hexagonal wurtzite structure AlN phases.The hardness of the W1?xAlxN films first increases and then decreases with the Al content increasing.The maximum hardness is36GPa,which is obtained at32.4%Al(mole fraction).Compared with WN film,the W1-xAlxN composite films show much better oxidation resistance because of the formation of dense Al2O3oxide layer on the surface.

NANOINDENTATION OF THIN-FILM-SUBSTRATE SYSTEM DETERMINATION OF FILM HARDNESS AND YOUNG'S MODULUS

In the present paper,the hardness and Young's modulus of film-substrate systems are determined by means of nanoindentation experiments and modified models.Aluminum film and two kinds of substrates,i.e.glass and silicon,are studied.Nanoindentation XP Ⅱ and continuous stiffness mode are used during the experiments.In order to avoid the influence of the Oliver and Pharr method used in the experiments,the experiment data are analyzed with the constant Young's modulus assumption and the equal hardness assumption.The volume fraction model(CZ model)proposed by Fabes et al.(1992)is used and modified to analyze the measured hardness.The method proposed by Doerner and Nix(DN formula)(1986)is modified to analyze the measured Young's modulus.Two kinds of modified empirical formula are used to predict the present experiment results and those in the literature,which include the results of two kinds of systems,i.e.,a soft film on a hard substrate and a hard film on a soft substrate.In the modified CZ model,the indentation influence angle,(?), is considered as a relevant physical parameter,which embodies the effects of the indenter tip radius, pile-up or sink-in phenomena and deformation of film and substrate.

Laser-Plasma Deposition of Silicon Carbonitride Films by the HMDS Vapor Gas Flow Activation after a Laser Beam Focus

A new laser-plasma deposition method has been developed for the plasma chemical deposition of hard silicon carbonitride coatings on stainless steel substrates from the hexamethyldisilazane (HMDS) Si2NH(CH3)6 vapor in a high-speed Ar and Ar + 10 vol.% He gas stream at the HMDS gas flow activation after the laser beam focus. The method allows depositing silicon carbonitride coatings at the rate of 0.4 - 1.2 μm·min-1, i.e. ~2 times higher than that at introducing HMDS in the laser beam focus zone. The properties of the prepared coatings have been studied by the methods of IR and Raman spectroscopy, atomic force microscopy, nanoindentation and X-ray diffraction (XRD) analysis. Studying the film structure with the use of XRD showed that the prepared silicon carbonitride coatings are X-ray amorphous. It has been found that the coating deposition rate and the structure of coatings depend on the process parameters: HMDS flow rate and plasma-generating gas (argon or (Ar + He). The method allows depositing SiCN films at a high speed and a hardness of 20 - 22 GPa.

PERFORMANCE AND MICROSTRUCTURE OF SUPERHARD Si_3N_4 FILM BY HIGH POWER CO_2 LASER CVD

A superhard α-Si_3N_4 film,deposited on metal substrate,was produced by laser chemical vapor deposition adopting a kW-level high power CO_2 laser.Most films are composed of fine Si_3N_4 partieles.They join the metal substrate in strong bond.The films have super hardness,excellent resistance to wear and corrosion,etc.Their thickness may be controlled within 5-30 μm.

Microstructures and properties of Si_3N_4/TiN ceramic nano-multilayer films

The polycrystalline Si3N4/TiN ceramic nano-multilayer films have been synthesized on Si substrates by a reactive magnetron Sputtering technique, aiming at investigating the effects of modulation ratio and modulation period on the microhardness and to elucidate the hardening mechanisms of the synthesized nanomultilayer films. The results showed that the hardness of Si3N4/TiN nano-multilayers is affected not only by modulation period, but also by modulation ratio. The hardness reaches its maximum value when modulation period equa1s a critical value λ0, which is about 12 nm with a modulation ratio of 3: 1. The maximum hardness value is about 40% higher than the value calculated from the rule of mixtures. The hardness of nano-multilayer thin films was found to decrease rapidly with increasing or decreasing modulation period from the Point of λ0. The microstructures of the nano-multilayer films have been investigated using XRD and TEM. Based on experimental results, the mechanism of the superhardness in this system was proposed.