Pyrolitic Carbon Research Articles

Boron-enriched pyrolitic carbon: material for biomedical and engineering applications

The article describes a technological set-up and the synthesis methodology of boron-enriched pyrolytic carbon (B-PyC). The chemical vapor deposition (CVD) approach lies in the basis of the methodology. The synthesis occurs on the inner surface of a cylindrical graphite assembly indirectly heated to the temperatures of 1450–1570 °C. Controlled low-density flows of nitrogen, boron trichloride and carbonaceous gases react in the assembly, producing a B-PyC film deposited on the graphite substrate. The set-up has been designed to provide fabrication of B-PyC plates possessing features required for heart valve endoprosthesis: chemical inertia and biocompatibility combined with high hardness, high elasticity, and long operating life. The morphology and chemical composition of the material have been studied by electron scanning microscopy and Raman spectroscopy. The material is used at the “Electronmash Plant” for fabrication of heart valve endoprosthesis leaflets.

Stress level estimates in coated or uncoated silicon nanoparticles during lithiation

This work is devoted to the modeling of the mechanical behavior of coated or uncoated silicon nanoparticles, which constitute the anode active material in some lithium ion batteries, during their first lithiation at room temperature. The lithiation process induces a large volume expansion of the particles and a high level of stresses, which can lead to the fragmentation of the particles. Several approaches are proposed in order to estimate the volume expansion and the stress levels experienced by the particles. An original semi-analytical small strain model is first presented, which adapts the solution proposed by Seck et al. (2018) of the elastic-viscoplastic composite sphere problem subjected to radial loading, to the lithiated particle problem, in particular by considering the variation of phases properties during lithiation. The lithium concentration in the silicon particle is given by a sigmoid function (called logistic function) in order to mimic the reaction front between the phases. The implementation of the approach using the Hencky strain tensor Miehe et al. (2002) is proposed to take into account the large strains experienced by the particles. A complete description of the formulation is provided and the advantages are discussed. The importance of the large strains model is established by comparing it with the small strain one concerning the predictions of the pushing-out effect and the size effect of particles on their internal stresses during lithiation. Comparisons between our simulations and experimental data from Tardif et al. (2017) measuring the operando strain experienced by the pristine silicon gives the yield stress of the lithiated silicon. In addition, carbon-coated silicon nanoparticles are finally studied. We develop original closed-form expressions to predict the maximal stresses experienced by the coating at the end of the lithiation. Those expressions are used to re-estimate the fracture stress of pyrolitic carbon, considering a critical review of both pyrolitic carbon and lithiated silicon elastic properties. Finally, the mechanical effect of the coating on silicon during lithiation is studied.

Short to Early-Mid Term Clinical Outcomes and Survival of Pyrocarbon Shoulder Implants: A Systematic Review and Meta-Analysis.

The appropriate surgical treatment option for young and active patients undergoing shoulder arthroplasty for arthritis remains questionable. Pyrolitic carbon (pyrocarbon) has been shown to improve implant longevity and decrease wear when in contact with cartilage or bone. The present systematic review aimed to evaluate clinical and radiological outcomes as well as the survivorship of pyrocarbon shoulder implants. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed. A systematic search was performed using the MEDLINE, EMBASE and Cochrane Library databases. All the studies dealing with the use of pyrolitic shoulder implants were pooled, data of interest were extracted and statistically analyzed through meta-analysis. A total of 9 studies were included for a total of 477 shoulders treated. The overall mean rate of survival of the implants was 93.4 ± 5.8% and 80% ± 26.5% at 2 years and final follow up, respectively, while resulting 82.4% ± 22.1% and 92.3% ± 3.5% for PISA (pyrocarbon interposition shoulder arthroplasty) and hemi-arthroplasty/hemi-resurfacing, respectively. Pyrolitic carbon shoulder implants showed good survivorship and clinical outcomes at an early to early-midterm follow-up. More studies and better-designed trials are needed in order to enrich the evidence on long-term outcomes and comparison with other shoulder replacement options for young and active patients. IV.

Sensitivity analysis applied to SiC failure probability in TRISO modeled with BISON

A sensitivity analysis on the failure probability of the Silicon Carbide (SiC) layer in tristructural isotropic (TRISO) nuclear fuel during transient conditions predicted by the BISON fuel performance code is performed. The principal goal of the analysis is to understand the most important parameters dictating SiC failure behavior in BISON during Reactivity Initiated Accidents (RIAs). SiC brittle fracture probability is modeled using Weibull statistics. A total of seven inputs related to SiC failure has been selected for the analysis, including the Weibull statistics parameters, elastic moduli for SiC and Pyrolitic Carbon (PyC) and SiC stress-free temperature. A 1D TRISO BISON model has been established for various reactivity insertions performed at the Nuclear Safety Research Reactor (NSRR). The principal advantage associated with the 1D TRISO model developed in this work is its computational efficiency. The Sobol variance decomposition method is used, and the sensitivity indices are presented for eight different values of the energy deposition. The results show that the two most important parameters impacting the predicted SiC failure probability are the Weibull modulus and the characteristic stress, and a co-variance amongst these parameters is obtained for low reactivity insertions. An additional new finding of this work is that the relative importance of Weibull parameters depends on the energy deposition, and thus reactivity, regime. For low energy depositions, two parameters are of influence on SiC failure probability, while for high energy depositions only one parameter impacts failure probability results. Moreover, optimization of the Weibull modulus and characteristic stress is performed by minimizing the RMSE between BISON failure probability predictions and experimental failure fractions for each energy deposition. This work also demonstrates the validity of the NSRR tests BISON simulations and of the respective sensitivity analysis results as conservative, yet indicative for slower transients characterized by lower deposited energies. Such verification is achieved through the partial extension of the analysis to a group Control Rod Withdrawal reproduced from a previous study. Another novel result of this analysis is that no single set of Weibull parameters can reproduce all reactivity insertion experimental failure results, which is related to the intrinsic nature of SiC failure properties, and a new range for the parameters is proposed to produce a failure probability envelope that encompasses the experimental fractions. Additionaly, this work proposes a new approach for future failure analysis with BISON, consisting in the use of Weibull parameters ranges, rather than fixed sets, along with failure envelopes generation.

Comparative insights into C/C–ZrC–SiC composites with different substrate carbon on microstructures, mechanical properties, and ablation behaviors

The microstructures, mechanical properties, and ablation behaviors of carbon-fiber reinforced carbon and ZrC–SiC ceramic matrix composites (C/C–ZrC–SiC) fabricated through reactive melt infiltration were systematically researched, of which preforms were densified using different substrate carbon: (i) resin carbon (RdC) and (ii) pyrolitic carbon (PyC) for comparison. The results showed that the densification process with pores that differ in location and size dominated the distribution of ceramic phases within pristine carbon-fiber reinforced carbon (C/C). In addition, the C/C–ZrC–SiC samples with different carbon substrates possessed different mechanical properties. The flexural strength of the C/PyC-ZrC-SiC composites was significantly higher, exhibiting a ductile fracture behavior, which is different from that of the brittle fracture model in C/RdC-ZrC-SiC composites. However, after being exposed to an oxyacetylene ablation torch at 2500 °C for 30–240 s, the C/RdC-ZrC-SiC composites exhibited better ablation resistances because there were more carbon matrix and carbide blocks per unit volume in the composites, and the structure of C/RdC-ZrC-SiC possessed a shorter healing time for pores during ablation. In other words, an integrated oxide scale on the ablated surface can be formed in a relatively shorter time. Therefore, the superior ablation behavior can largely be ascribed to the formation of dense oxides containing molten-like SiO 2 , which could effectively resist scouring and seal the pores promptly during ablation.

Prosthetic cardiac valves: history and review of cardiac prostheses clinically available in Japan.

Recently developed prosthetic valves are reliable and essential for the treatment of valvular heart disease. The mechanical valve evolved remarkably following the introduction of pyrolite carbon material, which enabled the creation of a bileaflet form incorporated with a pivot mechanism. The improved durability of the biological valve is attributed mainly to the development of a tissue fixation process and anti-calcification treatments. However, optimal antithrombogenicity and durability have not yet been achieved for either prosthetic valve type. To select the most suitable prosthetic valve for each individual patient from among the many clinically available prosthetic valves, it is necessary to have a thorough understanding of the characteristics of each valve.

Investigation of Zirconium Carbide Ceramic Coating on Surrogate Kernels Deposited by Plasma-Pulsed Laser Deposition: A Preliminary Study

High Temperature Gas-cooled Reactor (HTGR) is one of advanced nuclear reactors with high safety system feature. Indonesia has a plan to build HTGR as an Experimental Power Reactor (in Indonesian: RDE - Reaktor Daya Eksperimental). One of the safety system feature is its fuel system. There are two types of fuel of HTGR i.e. pebble bed type and prismatic type which all of the types are containing TRISO (Tri-Structural Isotropic) which consist of Inner Pyrolitic Carbon, SiC (Silicon Carbide) dan Outer Pyrolitic Carbon. One of the issues of the system is silver (Ag) and palladium (Pd) as the fission product could interact with SiC layer and cause corrosion. One of the candidate to resolve the issue is to replace SiC with ZrC (Zirconium Carbide). In this preliminary study, Zirconium Carbide ceramic has been deposited on a surrogate (uranium-free) fuel microkernels using PLD Plasma-Pulsed Laser Deposition. The parameter during ZrC deposition were temperature of 850°C for the substrate, the number of laser shots of 90,000 and the oxygen background gas with 40 sccm (standard cubic centimeters per minute) with the chamber pressure of 235 mTorr. Thereafter, the samples were analyzed using OM - Microscope Optic, SEM-EDS - Scanning Electron Microscope – Energy Dispersive X-ray Spectroscope, XRD – X-Ray Diffractometer and AFM – Atomic Force Microscope. The results exhibited that the ceramic coating could deposited on the surface of the substrate surface with homogeneously and sticky. The surface was very smooth within the nano-meter range order of ∼80-120 nm of surface roughness. Nevertheless, the results indicated that some of ZrC was react with oxygen at high temperature on the surface of the sample and deposited on the surface of surrogate microkernels.

Preparation of SiCf/SiC Composites with Low Porosity by Liquid Composite Moulding-Pyrolysis Process

Traditionally, Polymer infiltration and pyrolysis (PIP), chemical vapor infiltration (CVI) and melt infiltration (MI) are main processes to fabricate continuous silicon carbide fiber reinforced silicon carbide matrix (SiCf/SiC) composites, one of attractive potential high temperature structural materials. However, long preparation period and high porosity are still problems for further applications. Especially, porosity is crucial to the mechanical properties. Liquid composite moulding-pyrolysis (LCMP) used liquid SiC precursor to decrease the open porosity to 5% with no more than 11 cycles of infiltration and pyrolysis. Mechanical properties like bending strength was investigated with different thickness of pyrolitic carbon (PyC) interface and pyrolysis cycles. The bending strength reached 585 MPa with 200 nm PyC interface under 1200°C pyrolysis temperature. Thus, LCMP process offers exciting opportunities to improve performance of SiCf/SiC composites.

Susceptor Coating Materials Applicable for SiC Reactor Cleaning

In order to develop a cleaning process for the silicon carbide chemical vapor deposition reactor, the susceptor coating materials are developed for protecting the susceptor from the etching by chlorine trifluoride gas. The chlorine trifluoride gas does not give a serious damage to the pyrolitic carbon film at the temperatures lower than 480 °C, at which temperature the quick and practical reactor cleaning process is expected to be possible

A comparison between thermal-optical transmittance elemental carbon measured by different protocols in PM2.5 samples

Although controlled procedures for the determination of carbonaceous fractions are of importance for any air quality measurements, currently no reference method for elemental carbon (EC) and organic carbon (OC) analysis is established yet in Europe. The implementation of the different thermal evolution protocols available in the literature, differing in temperature and duration of the heating ramps, affects the results and can result in a wide variation of EC and OC values. In this study three different protocols for thermal-optical-transmittance analysis of EC and OC were compared, namely He-870 (a variation of the NIOSH protocol), He-550 (a proxy of the IMPROVE protocol), and EUSAAR_2. Measurements were carried out on PM2.5 samples collected on Quartz fibre filters in three sites of different typology: urban background and urban traffic in Florence (Italy) and regional background in Livorno (Italy). The samples were analysed before and after a washing procedure to remove possible water-soluble organic compounds (WSOC), which may enhance the charring process, complicating the EC quantification.This study evidenced a very good agreement for TC measurement (at 2–3% level) and some discrepancies in EC measurement (up to 40%), as expected. WSOC and Pyrolitic Carbon (PyC) present a good correlation, independently of site typology, demonstrating that water soluble compound can be responsible of charring mechanism during the He phase.

A robust approach to the design of an electromagnetic shield based on pyrolitic carbon

A robust approach to the design of an electromagnetic shield based on ultra-thin pyrolytic carbon (PyC, 5 ÷ 110 nm) films is proposed. Finite Element Method (FEM) simulations and Monte Carlo based tolerance analysis are used to show that even a deviation of 15 ÷ 20% from the nominal values of the most important design parameters of the PyC film, i.e. its thickness and sheet resistance, does not significantly affect the wanted level of electromagnetic interference shielding efficiency (EMI SE). The ranges of the SE show that EMI shield based on PyC film is characterized by a robust behavior with respect to the variation of such parameters due to the production processes. Therefore, since the PyC can be produced on a scalable basis, is chemically inert, significantly transparent in the visible range and can be deposited onto both metal and dielectric substrates, including flexible polymers, it may be appropriate for the highly demanding technological needs associated to the graphene revolution and can be developed from laboratory to mass production applications.

Small joints replacement for hand osteoarthritis: a systematic review.

Small joints replacement is a valid treatment for moderate to severe osteoarthritis of the hand. Several design and materials are now available for prostethic procedures with very different clinical and functional outcomes. An online search was carried out using Medline, Cochrane and Google scholar online databases, searching for studies on small joints replacement in hand surgery. Good functional and clinical outcomes can be achieved with silicone and pyrolitic carbon implants, either for trapeziometacarpal and metacarpophalangeal joints. In particular, the silicone spacer seems to be very effective for trapeziometacarpal osteoarthrosis, while the pyrolitic carbon total joint prosthesis produces excellent outcomes if used for metacarpophalangeal replacement. Major complications, such as persistent pain and implant loosening, have still a variable rate of occurrence. Heterogeneity in the methodology of the assessments in the studies reviewed and the implants and techniques involved makes it difficult to carry out a complete and effective comparative analysis of the data collected. Larger cohorts treated with the same implant should be investigated in better designed trials, to draw more clinically relevant conclusions from the evidences presented. Better methodology is also a goal to achieve, since the average Coleman Methodology Score measured for the articles included was 54.9 out of 100. More and better designed studies are needed to produce clear guidelines to define the better implant in terms of clinical outcomes, function and complications for trapeziometacarpal and metacarpophalangeal joints.

Evaluation of the Haemocompatibility of TiO2 Coatings Obtained by Anodic Oxidation of Ti-6Al-4V

The blood compatibility (haemocompatibility) is a requirement in materials used in prosthetic heart valves. No standardized methods are available to measure haemocompatibility in solid materials. However, a material could be considered haemocompatible if its surface does not modify the normal activation of the coagulation pathway and produces no damage in the blood components. In this work, the haemocompatibility of coatings obtained by anodic oxidation of Ti-6Al-4V (with H2SO4 1M and 40 to 70V) with and without heat treatment (1h for 500°C), is evaluated and compared with the haemocompatibility of the Ti-6Al-4V substrate and pyrolytic carbon. Standard clinical trials for clothing: Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) were adapted to evaluate the haemocompatibility of solid materials. Besides, the interaction between blood platelets and solid material were performed through an analysis of interfacial tension (γi,j), this parameter could indicate the degree of preferential adsorption of each protein of the blood plasma. The ratio between albumin-material and fibrinogen-material interfacial tension, (γs,Alb/ γs,Fib), is an important parameter used to predict the platelets adhesion and the trend at the formation of cloth. The results of the clothing trials indicate that the tested surfaces would be haemocompatibles due to the values of PT and APTT obtained which were in range of the normal ones. In addition, the measured values of γs,Alb/ γs,Fib indicate that all the tested surfaces are more haemocompatible than pyrolitic carbon. The recrystalized films by heat treatment which produce some rutile crystals are the most haemocompatibles.

Invited Commentary

This article reminds us of a disaster in cardiac surgery [1]. The first Björk-Shiley valve was implanted in 1969. In 1979 a convexo-concave disc was developed, and in 1980 the opening angle was increased to 70°. A free-floating pyrolite carbon disc was suspended in a stellite cage, constrained within the device by inlet and outlet struts. The outlet strut was welded to the prosthesis flange [2]. During the premarket trial, catastrophic failure occurred from outlet strut fractures. An increase in the strut clearance apparently eliminated the problems.

Trapeziometacarpal osteoarthritis: pyrocarbon interposition implants

the aim of this study was to evaluate the effectiveness of interposition arthroplasty of the trapeziometacarpal (TMC) joint with pyrolitic carbon implants for the treatment of TMC osteoarthritis. we evaluated two groups of patients surgically treated for TMC osteoarthritis: group 1 (34 patients - 36 TMC joints) treated with PyroDisk implantation and group 2 (25 patients - 25 TMC joints) treated with the Pyrocardan implant. All these patients were clinically evaluated at follow-up using the DASH score, Mayo Wrist score and VAS pain score. the mean follow-up was 42 months in group 1 and 12 months in group 2. Both groups showed good clinical outcomes in terms of pain relief, range of motion, and pinch and grasp strength. Revision surgery was needed in only one case in group 1 (2.8%) and in three cases (12%) in group 2. prosthetic replacement of the TMC joint was found to be a good solution for low-demand patients. However, the PyroDisk could be a good solution in selected patients (Eaton stage I-III, non-subluxated joint): it provides good pain relief, good range of motion, good pinch and grasp strength, and stable results at more than three-years of follow-up. Level IV, therapeutic case series.

Physicochemical Properties of Pyrolitic Carbon Black from Waste Tyres

Waste tyres which are mainly generated from automotive industries have become a major environmental problem to the local authorities, the tyre industries and tyre dealer. When tyres are no longer usable due to worn-out, defect or service failure they are usually dumped in the landfill sites. Pyrolysis is a process of the thermal decomposition of waste tyres in the absence of air and the oxygen. Pyrolysis may be an environmentally friendly process to transforms used tyres into gas, oil, steel and carbon black waste. The rate of recovery is 45 wt % for fuel, 30 wt % for carbon black and 10 wt % for steel wires for each end-of-life tyres. In this paper, the potential use of pyrolised carbon black generated from pyrolysis process of waste tyres is investigated. From the physical analysis of this carbon black waste, it was observed that there is various refraction particles sizes from the sieve test and different morphologies gathered from SEM analysis. Moreover, X-Ray Fluorescence (XRF) and TGA/DTG analysis on the carbon black waste showed high content of inorganic additives such as Silica (Si), Calcium (Ca) and Iron (Fe) which contaminate the sample. The carbon black waste started to decompose at a lower temperature of 480°C to 680°C compared to standard black at 500°C to 740°C. The test results gathered in this paper will act as a base-line towards alternative material or to replace the commercial carbon black available in the market.

Characterization of the porosity in TRISO coated fuel particles and its effect on the relative thermal diffusivity

A heat transfer model for a Tri-structural Isotropic (TRISO) coated fuel particle was developed using Image Based Modelling (IBM). Computed X-ray tomography at a resolution of 0.7μm was used to quantify the porosity of each layer. In order to study the thermal diffusivity of these coatings, an internal heat pulse was simulated in the kernel and the temperature, as a function of time, was measured from the surface of the Outer Pyrolitic Carbon (OPyC). Consequently, the half rise time of the temperature increase was found. The novel idea behind this technique is that once a heat pulse propagates through the particle layers, the half rise time of the temperature can be obtained from different spots on the OPyC surface. The article presents a correlation between the pore size distribution (measured by X-ray tomography) and the relative thermal diffusivity. The average porosities in OPyC (relative to the volume of the ceramic coating) measured using helium pycnometry, mercury intrusion porosimetry and X-ray tomography were 12.3vol%, 9.0vol% and 11.1vol%, respectively.

Beneficiation of Pyrolitic Carbon Black

This research investigated treatment of crude carbon black produced from pyrolysis of waste tyres in order to evaluate its quality and possible industrial applications. A representative sample of crude carbon black was dry screened to determine the initial particle size distribution. This was followed by pulverizing the crude carbon black and leaching in hot concentrated sulphuric acid for the removal of heavy metals and other contaminants. Analysis of the refined carbon black showed a significant improvement of the product quality compared to crude carbon black. It was discovered that refined carbon black can be further classified into multiple high value products for various industrial applications such as filler, paint pigment, activated carbon and fuel briquettes. Keywords—Activated Carbon, Briquettes, Fuel, Filler, Pyrolysis.

Interaction of Embedded Tri‐Isotropic Fuel Particles with Melt of Alkaline Borosilicate Glass

A silicon carbide (SiC) layer is an outer‐coated layer of spent tri‐isotropic (TRISO) fuel particles and it is known to be a pressure vessel for retaining fission products, and preventing contamination in the primary circuit of a nuclear reactor. The goal of this article is to elucidate the chemical bonding and an interface formation of an alkaline borosilicate glass (ABG) with the coating layer of TRISO fuel particles. Particular emphasis is placed on the analysis of the intermediate chemical phase at the interface SiC/glass as a function of the material impurity and thickness of the SiC layer. The findings provide valuable information regarding the restriction parameters of immobilisation TRISO particles in glass. The interaction between the glass and SiC caused a total destruction of a thin SiC layer (10 μm), a random partial interaction to a thick SiC layer (40 μm) and formation of bubbles (CO2, CO) to an inner pyrolitic carbon (IPYC). The Raman spectroscopy analysis revealed that the interaction of ABG with the SiC layer occurred at a point, where a low excess of carbon was co‐deposited during chemical vapour deposition process. The interaction resulted in a formation of a mono‐crystal SiC, dispersed in vitreous silica as a crystalline inclusion.

Growth of oriented vapor grown carbon fibers on pyrolytic carbon films without catalyst

Vapor-grown carbon fibers (VGCFs) have been of great interest to scientific and industrial communities for many years due to their unique crystalline structure as well as excellent physical and chemical properties [1–3]. They have potential applications as fillers in composites, superhigh hydrogen storage materials, and good electrode materials [4–8]. VGCFs are usually prepared by the decomposition of hydrocarbons, such as benzene and methane, using ultra-fine transition metal particles or their alloys as a catalyst at a growth temperature of 600–1300 C [9–11]. However, these methods sustain the disadvantage of introducing catalyst particles, which can make the synthesis process more complex, and the existence of catalyst must influence the properties of the products. Moreover, the mesoporous template or the d.c. bias was generally needed to enhance the growth of the oriented carbon nanotubes and carbon nanofibers [12, 13]. Recently, Lin et al. [14] prepared multi-walled carbon nanotubes on a porous carbon surface using carbon black as a substrate by the decomposition of diluted ethylene. Rantonen et al. [15] synthesized needle-shaped carbon filaments at low temperature by ultraviolet laser irradiation under nearand supercritical conditions without catalyst. These reports showed that the growth of carbon filaments without the aid of catalysts is possible. In this paper, microwave-assisted CVD method was used to prepare oriented VGCFs on pyrolitic carbon films by direct pyrolysis of methane without the use of any catalysts. The influence of reaction time (2, 10, 25, and 30 min) on the morphologies and structures of products at 1100 C was also discussed. The experiments were carried out in a vertical quartz tube heated in a home-made microwave furnace. The schematic of the experimental device is shown in Fig. 1. Carbon source gas is introduced into the gap between quartz tube and microwave absorbing materials, and then conducted out of microwave furnace via gas outlet. The silver-gray pyrolytic carbon films were deposited on the inner wall of quartz tube with a gas residence time of 0.1 s at 1000 C for 60 min by the microwave chemical vapor infiltration technique, and then used as the substrate. The reaction was conducted at 1100 C with the flow of mixture gas CH4/N2 (1:1 vol), for 2, 10, 25, and 30 min, respectively. After the reaction, the furnace was cooled down to room temperature in the atmosphere of N2. A layer of black filament-like substance deposited on the surfaces of the substrate was collected for analysis. The morphology and structure of products were characterized by field emission scanning electron microscopy (FESEM, Hitachi S-4700), and Raman spectroscopy (Renishaw Invia Reflex). The elemental composition of the materials was analyzed by an energy-dispersive X-ray (EDX) analysis technique attached to the scanning electron microscopy. Figure 2 shows typical FESEM images of oriented VGCFs with a uniform diameter of about 50 lm when the reaction time is 30 min. Figure 2a shows a side view of VGCFs formed on pyrolytic carbon film. It shows that the D. Fu F. Deng H. Sheng School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an, Shannxi 710072, China