Oxidation Resistance Performance Research Articles

Effect of Hf and B incorporation on the SiOC precursor architecture and high-temperature oxidation behavior of SiHfBOC ceramics

Polymer-derived ceramics (PDCs), such as silicon oxycarbide and its derivatives, show an exceptional high oxidative stability under extreme conditions. A novel multicomponent silicon oxycarbide system tailoring with transition metal (hafnium) and boron is fabricated by sol-gel and solvothermal method. Amorphous SiHBOC was formed via the condensation of Si–OH, B–OH and Hf–OH groups, respectively, and the bonds of Si–O–Hf and Si–O–B– were detected by FTIR and XPS characterization. After high-temperature pyrolysis, the precursor is converted to a rigid ceramic material that has an 85.8 wt % ceramic yield of SiHfBOC. We investigate the oxidation resistance performance of SiHfBOC using the isothermal oxidation test at 1400 °C. The results showed that the oxidative stability of SiHfBOC was significantly superior to than those of SiBOC ceramic.

Electrospun polyvinyl alcohol film containing pomegranate peel extract and sodium dehydroacetate for use as food packaging

Abstract An active polyvinyl alcohol (PVA) composite film incorporating pomegranate peel extract (PPE) and sodium dehydroacetate (SD) was prepared by electrospinning. The effects of the ratio of PPE to SD (1:0, 1:0.5, 1:1, 0.5:1, 0:1) in a consistent total mass fraction of ∼5% in the film forming solution were measured in terms of the physical properties, appearance, oxidation resistance, and antibacterial performance of the resulting films. When the ratio of PPE to SD was 1:1, the powder was uniformly dispersed throughout the film, and no obvious aggregation was observed via scanning electron microscopy. The results show that the addition of PPE and SD to PVA film can improve its elongation at break, but has no significant effect on its light transmission or water vapor permeability. Fourier transform infrared spectroscopy indicated that the interaction between PPE, SD, and PVA is complex. The addition of PPE to the film specimens resulted in obvious antioxidant activity. The results of bacteriostatic experiments showed that the antibacterial ability of the film against E. coli and S. aureus increased with increasing PPE and SD. This study thus quantifies the benefits of incorporating PPE and SD into PVA films for potential application as active packaging films or coatings.

Co-enhancement of oxidation resistance and mechanical properties of Cf/LAS composites: The effects of h-BN addition

Carbon fiber reinforced lithium aluminosilicate glass-ceramic composites have been extensively studied and widely used in industry applications, because of its good mechanical properties and low thermal expansion coefficient. However, further investigation is also need to improve its oxidation resistance and mechanical performance to meet higher requirements. In this work, Cf/LAS glass-ceramic composites were fabricated by a slurry impregnation and hot-pressing method with different amounts of h-BN. Results indicate that composites with 2 wt.% h-BN addition exhibit excellent flexural strength and fracture toughness, reaching 910 ± 22 MPa and 21 ± 1 MPa·m1/2, respectively, and that after oxidation at 600, 800 and 1000 °C for 1 h, their strength residual ratio can reach 47%, 35% and 32%, respectively. TEM analyses suggest the improvement of oxidation resistance and mechanical properties should be attributed to the unique interface of composites caused by h-BN addition.

Dense Mn1.5Co1.5O4 coatings with excellent long-term stability and electrical performance under the SOFC cathode environment

The long-term operation of intermediate temperature-solid oxide fuel cells (IT-SOFCs) could be significantly influenced by the stability of the interconnect itself, especially, its oxidation resistance under the cathode environment. In this work, dense 80-μm-thick Mn1.5Co1.5O4 (MCO) coatings were directly applied on T441 interconnects via cost-effective atmospheric plasma spray (APS) without any post-treatment. The MCO-coated T441 interconnect and La0.8Sr0.2MnO3(LSM)//MCO/T441 contact coupling were separately exposed to high-temperature oxidative environment to evaluate their long-term oxidation resistance and electric performance. A rather low area-specific electrical resistance (ASR) of 13 mΩ·cm2 was obtained for MCO-coated T441 at the end of 2000-h test cycle, and a similar decrement was observed for the LSM-MCO/T441 couple with a final ASR of 13.6 mΩ·cm2 at the end of 1200-h cycle. Electron back scattering diffraction was performed to explore the oxidation characteristic of the MCO/T441 interface. In addition, first-principles computations were conducted to evaluate the structural stability of various possible interfacial oxides using the Castep program based on the density functional theory. The results indicated that the APS-MCO coating exhibits high grain stability and effectively improves the oxidation resistance of the T441 interconnect during long-term operation under the SOFC cathode environment.

Spray drying formation of metal oxide (TiO2 or SnO2) nanoparticle coated boron particles in the form of microspheres and their physicochemical properties

In the present study, metal oxide (TiO2 or SnO2) nanoparticles were coated on boron particles using a facile spray drying technique. The coating of metal oxide nanoparticles on the boron surface was varied by changing the weight ratio of metal oxide nanoparticles to boron particles. The crystalline structure of the metal oxide nanoparticles was mainly retained without any additional phase formation on the metal oxide coated boron particles, as identified by XRD. FIB-SEM images showed that the TiO2 or SnO2 coated boron particles formed microspheres with diameters between 5 and 10 μm. FIB-cross sectional images indicated the microspheres had a porous structure, and every individual boron particle was coated by metal oxide nanoparticles. The line scanning profile, elemental mapping and corresponding EDAX spectra results indicated the boron particles were well coated with metal oxide nanoparticles, and confirmed the presence of respective elements in the samples, respectively. TEM study showed the fine coating of metal oxide nanoparticles on the surface of the boron particles. The surface elemental composition was identified with XPS, and revealed the strong interaction between the metal oxide and boron particles. The thermal behavior of the boron, metal oxide and metal oxide nanoparticle coated boron particles was studied in the presence of nitrogen and air atmosphere using thermogravimetric analysis. The TGA of the metal oxide nanoparticle coated boron particles showed enhanced oxidation-resistance performance in the presence of air atmosphere.

Microstructure and bonding performance of an Au-coated Ag alloy wire

An Au-coated Ag alloy (ACAA) wire was fabricated in this work. Microstructure and bonding performance including characteristics of free air ball (FAB) and heat affected zone (HAZ) of the ACAA wire was investigated. The wire is coated by Au layer with an average thickness about 110 nm continuously via physical method. During bonding, golf-clubbed FAB and asymmetrical distribution of Au on the section is observed. Sparking and heating from the side is suggested to be the reason and the schematic is illustrated. The ACAA wire experiences certain degree of grain growth in the HAZ. Tensile strength of the HAZ and base wire is 228.86 MPa and 232.43 MPa, respectively while elongation is 15.12% and 18.84%, meaning that the HAZ present slight tensile performance reduction. The ACAA wire presents better oxidation resistance, mechanical and electrical performance than the non-coated Ag alloy (AA) wire. Despite the golf-clubbed FAB, morphology of the bonded ball and bondability testing results of the ACAA wire meet the requirement of wire bonding.

Thermal and corrosion properties of V-Nb-Mo-Ta-W and V-Nb-Mo-Ta-W-Cr-B high entropy alloy coatings

High entropy alloys (HEAs) have drawn lots of attentions from researchers and industries because of their outstanding properties, such as high hardness, and good corrosion resistance. Particularly, the refractory high entropy alloy is characterized by its high temperature strength and stable thermal properties. We conducted the magnetron co-sputtering process to grow one V-Nb-Mo-Ta-W and three V-Nb-Mo-Ta-W-Cr-B refractory HEA coatings. The BCC phase of V-Nb-Mo-Ta-W HEA coating was changed into the amorphous-like structures when Cr and B elements were added into the coatings. Oxidation reactions occurred and very complex refractory metal oxides were produced on all HEA coatings when the oxidation was held at 800 °C in air for 1 h. The addition of Cr and B constituents into the V-Nb-Mo-Ta-W coating can provide good oxidation resistance and anti-corrosion performance. The highest hardness of 18.4 ± 0.5 GPa, an excellent corrosion resistance at room temperature, a high hardness of 15.9 ± 1.1 GPa and good thermal stability after 500 °C oxidation test were obtained for the V10.4Nb10.5Mo10.5Ta11.2W10.5Cr16.3B28.6 refractory HEA coating in this study.

Microstructure and high temperature oxidation resistance property of packing Al cementation on Ti-Al-Zr alloy

The aluminide coating was prepared on Ti-6Al-2Zr-1Mo-1 V titanium alloy by pack cementation to enhance the high temperature oxidation resistance for aircraft and aerospace applications. High temperature oxidation behaviors of packing cementation coated and uncoated titanium alloy samples were comparatively investigated by isothermal oxidation at 800 °C and 900 °C in air. The results show that the compact coating with about 60 μm thick was composed of TiAl3. With isothermal oxidation for 100 h at 800 and 900 °C, the weight gains of the coated samples are 1.29 mg·cm−2 and 4.06 mg·cm−2 respectively, which are about 2/5 and 1/5 of that of titanium alloy substrates (3.20 mg·cm−2 and 20.33 mg·cm−2). The excellent oxidation resistance performance is attributed to the formation of a continuous and dense Al2O3 layer on the TiAl3 coating surface, which was effective to prevent the O element diffusing into the coating and then reduce the oxidation rate.

Evolution of microstructure and anti-oxidation ability of ZrB2 improved by a unique inert glass phase

Abstract Zirconium Boride is widely used as thermal protection materials. However, the characteristics of poor oxidation resistance of ZrB2 at high temperatures limits its applications. In order to improve the anti-oxidation performance of ZrB2, a novel method of doping LaF3 is adopted in present study. In the synthesis process of ZrB2 via carbothermal reduction method, LaF3 was introduced to the initial materials. Motivated by the slightly higher formation temperature of ZrB2 than the melting point of LaF3, a liquid glass phase composed of F and La was deposited on the surface of ZrB2, which naturally brought in oxygen starvation and contributed to improved oxidation resistance performance. The crystal lattice parameters and the anti-oxidation ability of ZrB2 are closely dependent on the added LaF3 content, which can ascribe to La3+/Zr2+ substitution and the amount of glass phase on the surface of ZrB2.

Size‐Dependent Activity of Iron‐Nickel Oxynitride towards Electrocatalytic Oxygen Evolution

AbstractThe exploration of efficient nonprecious metal‐based oxygen evolution reaction (OER) electrocatalysts is of great significance. Herein, both size‐ and component‐tuned FeNi oxynitride are prepared and employed for electrocatalytic water oxidation. Combining the excellent metal‐like feature of induced OER activity of nitrides and oxidation resistance performance of oxides, the obtained FeNi oxynitride delivers an outstanding OER performance. The synergistic interplay between Fe, Ni components creates a favorable local coordination environment for OER and decreased sizes enables more active sites exposure. As a result, under 1 M KOH, the optimized material displays highly efficient electrocatalytic OER performance with low overpotential 295 mV (10 mA cm−2 catalytic current density) and considerable durability. These findings open up opportunities to explore other excellent catalysts through multicomponent strong interactions coupled with size control.

Preparation and properties of silver-coated copper powder with Sn transition layer

A silver-coated copper powder with an added transition Sn layer is obtained by electroless plating, and the prepared composite powder is heat-treated under a protective atmosphere to form a transition layer by diffusion between metal atoms for improved powder properties. The effect of the transition layer on the morphology, adhesion and oxidation resistance of the copper-coated copper powder is studied. The results show that the Cu/Sn/Ag composite powder exhibits excellent plating adhesion and oxidation resistance performance when the content of the intermediate layer is 10% of Sn.

Synthesis of a Multi-phenol Antioxidant and Its Compatibility with Alkyl Diphenylamine and ZDDP in Ester Oil

In this study, a multi-phenol antioxidant 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylthio)-1,3,5-triazine (THA) was synthesized. The thermal stability of THA and its oxidation resistance in triisodecyl trimellitate (TDTM) ester oil were evaluated compared with several commercial phenol antioxidants. Further investigations on the oxidation resistance and tribological performance of THA with dinonyl diphenylamine (Am) and ZDDP composites were conducted to determine the additive compatibility in TDTM. The results indicate that the THA possesses higher thermal stability and more effectiveness of oxidation resistance than the commercial phenol antioxidants. The synergistic anti-oxidative effect is confirmed for the THA/Am mixtures in TDTM ester oil. However, the addition of THA alone or THA/Am mixtures shows no improvement for the tribological performance of TDTM. Excitingly, the THA/Am/ZDDP composite additives not only have the superior oxidation resistance, but exhibit the effective friction and wear reductions. It suggests the excellent compatibility of the synthesized THA antioxidant with Am and ZDDP additives in TDTM ester oil.

Microcrystal structure evolution of mesophase pitch-based carbon fibers with enhanced oxidation resistance and tensile strength induced by boron doping

Abstract Mesophase pitch-based carbon fibers (MPCFs) with various concentration of boron were fabricated through an easy and effective strategy by treating stabilized fibers with boron acid solution. The microstructural evolution of boron-doped MPCFs was characterized. It was found that boron doping promoted high degree of graphitization with the decrease of interlayer spacing and the growth of crystallite dimension due to catalytic graphitization of boron to carbon. Boron doping significantly improved 5 wt% burn-off temperature of MPCFs increasing by 344 °C, and the tensile strength of MPCFs was also enhanced by 19%. Both of the outstanding oxidation resistance and mechanical performance of MPCFs was obtained due to effect of boron. The results demonstrated boron doping was a feasible way to produce high-performance MPCFs.

Efficient novel amphiphilic double shells layer coupled with nanoscale zero-valent composite for the degradation of trichloroethylene

An efficient novel amphiphilic material composed of core-double shells nanocomposite (CDSN) with nanoscale zero-valent iron (NZVI) as the core and PS100-b-PAA16 as inner shell and chitosan as outmost shell has been synthesized successfully. Its application to remove the trichloroethylene (TCE) in stimulated TCE solution with 7.3 ± 0.3 mg/L dissolved oxygen was investigated. The results showed that CDSN after exposure to air for a month could still remove 92.6% of TCE as compared to 61.5% removal rate of NZVI in 360 min (the gram ratio of material: TCE equals to 10:1), exhibiting the great oxidation resistance performance. Specifically, dynamic research of the total removal divided into adsorption by shell layer and degradation by reducibility of NZVI at a predetermined interval was engaged to understand the complete mass transfer process of TCE. The results revealed that CDSN adsorbed 1.5 to 2 folds time TCE as compared to NZVI in the same initial pH = 8.5 aqueous solution. Importantly, CDSN could sustain fixed reactivity to remove about 94.8% of TCE from the start to end. NZVI exhibited greater removal capacity in first 180 min, but later it lost the reducibility and finial removal rate was 89%. The selective adsorption to protonated CDSN was strengthened to increase the removal of TCE at pH 3.5 while NZVI had a worse removal in pH 3.5 performance than pH 8.5.

Oxidation protection of C/C composites: Coating development with thermally stabile SiC@PyC nanowires and an interlocking TaB2-SiC structure

To improve the thermal stability of SiC nanowires at ultra-high temperatures, pyrolytic carbon (PyC) is deposited on them by chemical vapor deposition. The results suggest that the PyC can effectively protect nanowires from phase transition and crystal growth up to 2373 K. Meanwhile, a PyC-coated SiC (SiC@PyC) nanowire-reinforced interlocking zigzag interface is designed and constructed between TaB2-SiC coating and carbon/carbon (C/C) composites. Due to more survivals of nanowires and the constructed zigzag interface, adhesion strength of TaB2-SiC coating is enhanced. During the thermal cycling test between 1873 K and room temperature in air, SiC@PyC nanowire-reinforced interlocking TaB2-SiC coating prepared by pack cementation (PC) technique, exhibits good oxidation-resistant performance. The alleviation of coefficient of thermal expansion and the buffering roles of PyC effectively decrease the thermal stress of TaB2-SiC coating and restrain the formation of microcracks. These results can provide useful information for nanomaterial-reinforced ceramics and ceramic coatings to be employed at ultra-high temperatures.

Phase evolution, nanostructure, and oxidation resistance of polymer derived SiTiOC ceramic hybrid

Si based polymer-derived ceramics (PDCs) have emerged as potential materials in the fabrication of thermo-structural composites. Among the many PDCs, silicon oxycarbide (SiOC) can be fabricated from commercially available polysiloxanes and/or polysilsesquioxanes. However, SiCO based PDCs exhibit relatively limited oxidation resistance and high temperature performance compared to nitride/carbonitride counterparts. In addition, these ceramics should be compatible with carbide based substrates and oxide based top coats for thermal protection systems. Present work indicates that the incorporation of titanium into the Si-O-C system exhibits interesting properties such as crystallization, oxidation, and thermal stability. Commercially available polymethylphenylsilsesquioxane was doped with 5–20 mol% of titanium crosslinked and pyrolyzed in inert atmosphere at various temperatures. It was found that Ti ions crystallize into carbide phase at temperatures as low as 1200 °C, and that the phase separation of SiO2 shifts to temperatures beyond 1300 °C. Electron microscopy indicated the formation of nanostructured precipitates of SiC and TiC, in the size range of 4–12 nm for different conditions, with exceptional homogeneity throughout the matrix. Ab initio calculations, hypothesis based on simple bond-counting method, also confirms possible feasibilities of the doping of Ti into the SiOC structure. The SiTiOC ceramic hybrids exhibited only 17% loss on oxidation as against 41% for the SiOC ceramics. This approach indicates great promise for the application of commercial silicone polymers as high temperature resistant coatings.

The influence of carbides on the microstructure, grain growth, and oxidation resistance of nanostructured carbides-strengthened cobalt-based multi-track laser-cladding layers

Cladding layers were prepared on carbon steel using nanostructured carbide-strengthened cobalt (Co)-based alloy (using nanostructured tungsten carbide as hard phases) as a deposited material by multi-track laser cladding. In addition to Co-based alloy, the deposited materials contained nanostructured chromium carbide (Cr3C2), vanadium carbide (VC), or Cr3C2 and VC. Compared with the substrate, all cladding layers had an improved oxidation resistance with an increased time (0–50 h) at 800 °C. Cr2C3 had a higher oxidation-resistance performance than VC and the mutual reaction of Cr2C3 and VC. The constitution and phases of the cladding layers indicated hexagonal-close-packed-α and body-centered-cubic-β cobalt and hard carbides, such as CoCx, V8C7, and Cr3C2, and some decarburization as Co3W3C and WC1-x. Elemental inter-diffusion occurred between the different phases as indicated by transmission electron microscopy and electron backscattered diffraction. Mixed carbide has a larger misorientation than the cobalt matrix, and electron backscattered diffraction has considerable potential to evaluate plastic deformation. The average grain size of the hard carbides was much larger than that of the original deposited material. The carbides grew rapidly through interfacial diffusion, boundary migration, and coalescence, which followed the Kirkendall effect and Ostwald-coarsening mechanism. This research helps to understanding the microstructure, oxidation resistance, grain growth, and interfacial behavior in multi-track laser-cladding layers.

Preparation, modification and characterization of plasma sprayed graphite/SiO2 powder and related coating

During the fabrication of functional high-endothermic-enthalpy graphite/SiO2 composite coating, the oxidation and vaporization of raw materials have become serious issues in hyperthermal preparation environment. In this study, these issues were addressed through densification and modification of the feedstock powder. Then, the corresponding coating was prepared by optimized plasma-spraying parameters. By investigating the modified feedstock powder and the resulting splats and coatings by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy, we realized an optimized composite feedstock powder preparation process and an ideal coating structure. The compactness of the powder reached its optimum after treating at 1400 °C for 2 h. After heat treatment densification and Ni shell covering processes, the modified powder exhibited good oxidation resistance, vaporization resistance, and spreading performance during plasma spraying. Thus, a pure and dense composite coating was prepared. Positive laser resistance performance was observed during the initial laser ablation test, which proved that this modified graphite/SiO2 coating has good application potential in the laser protection field. Moreover, this study provides an experimental basis and a feasible method for difficult-to-spray composite coatings’ preparation, such as graphite/SiO2 composite.

Microstructural evolution of SiC coating on C/C composites exposed to 1500 °C in ambient air

Oxidation-resistant coatings are essentially required to improve oxidation resistance performance of carbon/carbon (C/C) composites for applications under oxygen-containing atmosphere at elevated temperatures. In this work, thick and loose SiC coating was prepared by pack cementation (PC) to offer protection for C/C composites. Coating thickness, phases, anti-oxidation properties, and failure behavior at 1500 °C were characterized in ambient air for the as-prepared SiC coated specimens. As-prepared loose SiC coating with 150 µm thickness shows good oxidation resistance due to outstanding self-heal ability of SiO2. Weight loss of SiC coated specimens exposed to 1500 °C in ambient air is about 2.1% after oxidation for 58 h. Microstructural observation of SiC coated specimens after long-term oxidation indicates that bubbles caused by immigration and expansion of CO2 gas introduce defects. These defects cannot be rapidly healed by SiO2, which is main reason for SiC coating failure.

Fabrication and microstructure evolution of Al2O3/ZrBN-SiCN/Al2O3 high-temperature oxidation-resistant composite coating

The oxidation-resistance of thin film sensors, particularly at high temperatures, is critical for the lifetime and performance of the sensor. The preparation and oxidation-resistance of an Al2O3/ZrBN-SiCN/Al2O3 composite film with a sandwich-structure was performed using reactive magnetron sputtering. The microstructure evolution of the composite film is examined herein using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. Oxygen diffusion was significantly inhibited by the formation of crystalline Al2SiO5 and Zr-B-C amorphous phase inside the composite film. The Pt-13%Rh/Pt thin film thermocouple (TFTC) with the Al2O3/ZrBN-SiCN/Al2O3 composite film as a protective layer was fabricated and calibrated. Both the stability and lifetime of the TFTC was significantly enhanced for temperatures up to 1000 ℃. The test error of the TFTC was reduced by half, compared with that of the TFTC with the Al2O3 protective layer, indicating an excellent oxidation-resistant performance of the composite film.