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1.
《Ceramics International》2022,48(18):26028-26041
Multilayered C–Si–Al coatings with various morphologies were deposited on carbon fibers (CFs) using magnetron sputtering. The thickness of the coatings was increased from 0.5 to 1.5 μm by magnetron sputtering between 90 and 120 min. C–Si–Al coatings of suitable thickness were heat-treated at 600 °C and transformed into C–Si–Al2O3 coatings by one-step anodic oxidation (AO). The oxidation time for the one/two-step anodic oxidation and the ratio of oxidation time for the two-step anodic oxidation significantly influenced the morphologies of the C–Si–Al2O3(AO) coatings. Al2O3 coatings with satisfactory morphologies and structures were prepared by two-step anodic oxidation with a total time of 30 min and a ratio of 1:1 between the initial and secondary oxidation times. The multilayered C–Si–Al2O3(AO) coatings were modified to C–Si–Al2O3 coatings by secondary heat treatment at 1050 °C. Subsequently, hot-press sintering was used to prepare CFs with multilayered C–Si–Al2O3 coating-reinforced hydroxyapatite (CF/C–Si–Al2O3/HA) composites. The multilayered C–Si–Al2O3-coated CFs demonstrated good resistance to oxidation and thermal shock. This could effectively protect CFs from oxidative damage and maintain its strengthening effect during sintering. The multilayered C, Si, and Al2O3 coatings effectively reduced the difference between the coefficient of thermal expansion of the CFs and HA matrixes. The interfacial gaps between the multilayered coatings and HA were reduced. This could enhance the mechanical performance of the composites. The CF/C–Si–Al2O3/HA composites exhibited improved mechanical properties with a bending strength of 83.94 ± 12.29 MPa, and fracture toughness of 2.45 ± 0.08 MPa m1/2. This study can broaden the application of CF/C–Si–Al2O3/HA biocomposites as bone-repair materials and help obtain CF-reinforced composites with excellent mechanical properties that are fabricated or serviced at high temperatures. 相似文献
2.
Cheng‐Ho Chen Ming‐Kun Ou Shin‐Hsiang Lin Ming‐Shyong Tsai Ching‐Feng Mao Fu‐Su Yen 《应用聚合物科学杂志》2006,102(6):5747-5752
This study focuses on the preparation of an organic–inorganic ultraviolet (UV) curable coating containing the nanoscale α‐aluminum oxide (α‐Al2O3) powder and UV curable resin. This developed coating can form a protection film on the poly(vinyl chloride) (PVC) plastic tile surface. Thus, the abrasion resistance of the PVC plastic tile surface is improved. Besides, the adhesion between this UV cured film and the PVC plastic tile surface is well. After treatment with the UV curable coating that contains 6 wt % α‐Al2O3, the abrasion resistance of the PVC plastic tile surface can be improved up to 57%. From the result of a scanning electron microscopy (SEM) mapping photograph, it shows that the nanoscale α‐Al2O3 powder is well dispersed in the cured coating film. Under the wavelength of the visible light in the range of 400–800 nm, the degree of transparency for the coated film on poly(ethylene terephthalate) (PET) sheet is about 82–90%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5747–5752, 2006 相似文献
3.
In this study, Al2O3/CrAlSiN multilayer coatings with various periods were prepared using a hybrid process involving overlapping magnetron sputtering of CrAlSiN and atomic layer deposition (ALD) of Al2O3. The influence of the number of Al2O3 layers on the mechanical properties, corrosion behavior and oxidation characteristics of the coatings was studied using nano/micro indentation, electrochemical corrosion, and high temperature static oxidation tests. The results show that the multilayer structure can effectively prevent crack propagation during the coating and subsequently increase the coating toughness. A substantial improvement in the resistance to electrochemical and oxidation corrosion was observed in the Al2O3/CrAlSiN multilayer coatings and increasing the number of Al2O3 layers dramatically increases the corrosion durability. The Al2O3 ALD layers are expected to inhibit the diffusion of corrosive substances such as ions and oxygen and the increase of the Al2O3 layer number decreases the diffusion fluxes of the coating elements to the surface and limit the oxide growth, resulting in the evolution of the oxidation produces from irregular particles to nano-walls/fibers. It is supposed that the PVD/ALD hybrid process may open a new hard coating design concept by providing a superior toughness and corrosion/oxidation resistance. 相似文献
4.
Xiang Yang Zhang Wen Chen Kun Li Yong-kang Peng Zhi-hang Sun Chen-cheng Wu Wen-jun Cao Jian-hui 《International Journal of Applied Ceramic Technology》2022,19(6):3267-3278
Continuous alumina fiber–reinforced alumina matrix composites (Al2O3f/Al2O3 composites) were produced via sol–gel process, then the high-temperature mechanical property and thermal shock resistance of Al2O3f/Al2O3 composites were investigated. The results showed that the composites exhibited excellent high-temperature properties. The mechanical property of the composites was affected by heat treatment (prepared at 1100°C exhibited the most desirable mechanical property). The tensile strength of the composites abruptly decreased at higher temperatures. Although the mechanical property of the composites deteriorated after the thermal shock test was conducted at high temperatures, they exhibited excellent thermal shock resistance. After 50 thermal shock tests conducted at 1300 and 1500°C, the flexural strength of the composites was found to be 124.34 and 93.04 MPa, thus showing a decrease in strength with the increasing temperature. 相似文献
5.
《Ceramics International》2020,46(6):7774-7782
In order to inhibit the metal catalytic coking and improve oxidation resistance of single TiN coating, the TiN/Al2O3 double layer coatings were designed as a chemically inert coating for methylcyclohexane supercritical pyrolysis. Internal TiN coatings were prepared by atmospheric pressure chemical vapor deposition using TiCl4–H2–N2 system. The external Al2O3 coatings with different thicknesses were prepared on the TiN surface by polymer-assisted deposition, and the coating with the most suitable thickness was further annealed at different temperatures of 600, 700, 800 and 900 °C. The morphology, elemental and phase composition of TiN/Al2O3 coatings were characterized by SEM, EDX and XRD respectively. The chemical state information of the coating elements was based on Ti 2p, Al 2p core level X-ray photoelectron spectroscopy (XPS) spectra. The results indicated that the external Al2O3 coating will partially peel off at 900 °C annealing temperature. The thermogravimetric analysis results indicated that all TiN/Al2O3 coatings show better oxidation resistance than single-layer TiN coating. The anti-coking test with methylcyclohexane supercritical pyrolysis showed that the TiN/Al2O3 coatings can effectively cover the metal catalytic sites and eliminate metal catalytic coking. However, the acid sites of external Al2O3 coating slightly promoted coking, so the anti-coking ratios of TiN/Al2O3 coatings were smaller than that of TiN. Thus, the addition of external Al2O3 coating can greatly improve the oxidation resistance of TiN coatings with little loss of coking resistance. 相似文献
6.
《Ceramics International》2023,49(6):9231-9238
This work looked at the in-situ formation mechanism of magnesia alumina spinel in Al2O3–C refractories with magnesia addition at different firing temperatures. A comprehensive study on the mechanical properties of Al2O3–C refractories was performed in comparison to traditional analogs. The magnesia alumina spinel was in-situ formed at the firing temperature of 1150 °C in Al2O3–C refractories. With the increase of the firing temperature, the Al2O3 phase was gradually dissolved in spinel phase to form aluminum rich spinel phase, resulting in a decrease in its lattice constant due to the defects formation. The formed spinel phase was homogenously distributed and bonded well with corundum, improving the interfacial bond, load transferring capacity and crack propagation resistance. The formation of spinel phase also enhanced the sintering of the alumina matrix owing to the solid solution of alumina in the spinel. Therefore, the mechanical properties such as cold modulus of rupture and hot modulus of rupture in Al2O3–C refractories achieved a substantial enhancement compared with traditional refractories. 相似文献
7.
Rundong Fan Huizhong Zhao Han Zhang Pengda Zhao Jianwei Chen Xianghui Wang 《Ceramics International》2019,45(9):11204-11215
Alumina–chromium slag (ACS), a cheap and abundant refractory raw material comprising aluminum–chromium oxides and β-Al2O3, is a byproduct of ferrochrome smelting. For this reason, we investigated the relationships between composition and mechanical properties, abrasion resistance, oxidation resistance, and resistance to iron slag erosion for Al2O3–SiC–C trough castables in which ACS was substituted for alumina. Due to the presence of β-Al2O3 in ACS, the aluminum-chromium slag reacted with SiO2 to form a low-melting phase of albite and promoted the formation of mullite, which filled the pores at high temperatures and reduced the porosity, thereby promoting densification and strengthening of the sample. The cold mechanical properties of the sample and the normal temperature wear resistance were enhanced, but the high-temperature mechanical properties and the resistance to iron slag corrosion of the sample were impaired. According to the results of the anti-oxidation experiment, the presence of β-Al2O3 in the ACS reduced the porosity and made the sample more dense, which remarkably improved oxidation resistance of the sample. For industrial production requirements, ACS substitution should not exceed 48?wt% due to of thermomechanical properties and anti-slag corrosion performance in Al2O3–SiC–C trough castables. 相似文献
8.
Mengyao Yang Guoqing Xiao Donghai Ding Yifan Yang Mingxue Jiang Dingao Yang Shouqian Yuan 《Ceramics International》2021,47(16):22949-22956
The Al–Al2O3 composites were prepared by fused alumina, α-Al2O3 micropowders, and metal aluminum powder. The samples with 3% carbon black (N330), 3% resin powder and α-Al2O3 micropowder, 10% α-Al2O3 micropowder were named S1, S2, and S3, respectively. They were oxidized at 1500 °C for 3 h in a box-type electric furnace, and then the unoxidized areas were analyzed by X-ray diffraction and scanning electron microscopy. It was found that the aluminum oxycarbonitride formed in situ during the oxidation resistance test inhibited further oxidation of S2. The in situ formation mechanism of aluminum oxycarbonitride in the unoxidized zone is believed to be 7Al + 3Al3C4 + 12AlN + 4Al2O3 = 12Al3CON, which is also verified and proven by XRD, SEM and EDS in this work. The oxidation depth of S2 is 46.7% lower than that of S3. Sample S2 hardly has any linear change after fired at 1500 °C × 3 h in coke, which benefits to improve the volume stability and prolongs the service life. Among the three batches, S2 exhibits the minimum creep rate, from 0% to 0.026% at 1500 °C, and the HMOR at 1500 °C in a N2 atmosphere of S2 is 58 MPa. The Al–Al2O3 composites combined with resin strengthened by in situ formed aluminum oxycarbonitride give the composites excellent high-temperature strength owing to the fiber-intersected reinforced microstructure of Al3CON crystals at high temperature. In the Al–C–N–O system, it was found that the general formula of aluminum oxycarbonitride is expressed by Al4n+m(C,O,N)3n+m, and the (n, m) values are (0, 3) for Al3CON. 相似文献
9.
Phase evolution mechanism of non‐oxide bonded Al–Al2O3–MgO–ZrO2 composites at 1873 K in flowing nitrogen
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Mingwei Yan Yong Li Jiaojiao Wang Hongyu Li Yang Sun Chenhong Ma 《Journal of the American Ceramic Society》2018,101(5):2162-2169
In flowing nitrogen, non‐oxides such as Al4O4C, Al2OC, Zr2Al3C4, and MgAlON bonded Al2O3‐based composites were successfully prepared by a gaseous phase mass transfer pathway using aluminum, zirconia, alumina, and magnesia as raw materials at 1873 K, after an Al–AlN core‐shell structure was formed at 853 K. Resin bonded Al–Al2O3–MgO–ZrO2 composites after sintering were characterized and analyzed by X‐ray diffraction (XRD), scanning electron microscope (SEM) and, energy dispersive spectrometer (EDS), and the influence of the MgO content on the sintered composites was studied. The results show that after sintering, the phase composition of the Al–Al2O3–ZrO2 composite is Al2O3, Al4O4C, Al2OC, and Zr2Al3C4, while the phase composition of the Al–Al2O3–ZrO2 composite with the addition of MgO 6 wt% and MgO 12 wt% is Al2O3, MgAlON, Al4O4C, Al2OC, and Zr2Al3C4 as well as Al2O3, MgAlON, Al2OC, and Zr2Al3C4, respectively. The addition of MgO changed the phase composition and distribution for the resin bonded Al–Al2O3–MgO–ZrO2 system composites after sintering. When the added MgO content is equal to or more than 12 wt%, the Al4O4C in the resin bonded Al–Al2O3–MgO–ZrO2 system composites is unable to exist in a stable phase. 相似文献
10.
JinKiong Ling Bhupender Pal KwokFeng Chong Lukas Schmidt-Mende Juan Bisquert Rajan Jose 《Journal of the American Ceramic Society》2019,102(10):6337-6348
Suppression of charge recombination by thin amorphous alumina layers on metal oxide semiconductors has demonstrated a vital role in electronic appliances beside its role as an insulator. This study reports effect of amorphous alumina (Al2O3) on the structural, electrical, and optical properties of stannous oxide (SnO2). The samples for the present study are prepared as nanofibers by electrospinning a polymeric solution containing aluminum and stannous precursors and subsequent annealing; six samples with varying concentrations of aluminum and stannous are considered. A crystal-amorphous SnO2/Al2O3 hybrid system was confirmed by both XRD and XPS analysis. Both BET and Mott-Schottky analysis showed increase in the surface area and conduction band minimum of the sample with increase in the Al content, however, at the expense of its electrical conductivity. The electron lifetime of the sample increased with increase in the Al content, but the electron transport time increase with decrease in the electrical conductivity of the sample. Both Urbach energy measurement and Stoke's shift showed generation of deeper trap state with increase in the Al content. Investigation on sample photovoltaic performance showed that the loss in electrical conductivity of the sample can be compensated by the improved surface area to a certain extent. Interestingly, a composite nanofiber containing equal molar fraction of aluminum and stannous showed orders of magnitude higher photocurrent despite its similar resistivity as that of pure alumina fibers, which is shown to originate from a Fermi energy gradient at the Al2O3/SnO2 interface. 相似文献
11.
The effectiveness of a novel coating method in providing fine iron powder particles with a protective barrier against rapid oxidation was systematically studied. Particles were individually coated with an alumina‐based (Al2O3) ultra‐thin film using the Atomic Layer Deposition method. The oxidation resistance of the coating layer was found to be greatly dependent on the film thickness. Furthermore, for each film thickness there was a corresponding temperature above which the film drastically lost its protective effectiveness, primarily due to cracking caused by the thermal expansion mismatch between the particle and the alumina film. This problem was largely overcome when, instead of Al2O3, the protective film was generated from alternating layers of Al2O3/ZnS to ensure that the thermal expansion properties of the resultant film matched that of iron. The technique employed in this study is quite robust and can be adapted for combustion prevention in other types of metal powders. 相似文献
12.
《Ceramics International》2020,46(4):4215-4221
Alumina is widely used as a coating on a metal implant due to its favorable mechanical and biological properties. In this research, in order to improve mechanical and biological properties of alumina, a composition of nanoparticles of alumina (instead of microparticles) and titanium diboride micro powder is introduced. The atmospheric plasma spray (APS) technique was applied to deposit Al2O3–TiB2 on the pure titanium substrate. The properties of Al2O3–TiB2 nanocomposite coatings with various weight percent of TiB2 (20, 30 and 40 wt%) were experimentally studied. The characteristics of nanocomposite films of TiB2 (20, 30 and 40 wt%) were analyzed using Field Emission Scanning Electron Microscopy (FE-SEM), energy dispersive electron spectroscopy (EDX) and X-Ray Diffraction (XRD) tests. The XRD spectra exhibited that in addition to alumina and titanium diboride, the films contained titania. Thickness and morphology of the films were calculated from FE-SEM images and the thickness of the optimized coating (Al2O3-30 wt% TiB2) was about 30–45 μm. Also, the roughness, corrosion resistance, hardness and cytotoxicity (MTT) tests were studied. The highest of hardness and roughness of the samples were obtained from Al2O3-30 wt% TiB2. According to the obtained results from the polarization test, Al2O3-30 wt% TiB2 coating had the highest corrosion resistance (222558.9962 Ω cm2). Therefore, the toxicity of Al2O3-30 wt% TiB2 was investigated as the optimized coating and the results confirmed its non-toxicity and biocompatibility. 相似文献
13.
Xuan Wang Chengji Deng Jinghui Di Guangchao Xing Jun Ding Hongxi Zhu Chao Yu 《Journal of the American Ceramic Society》2023,106(6):3749-3764
The synergistic effects of Al3BC3–Al antioxidants on optimizing the oxidation resistance of low-carbon MgO–C refractories were investigated. The results indicated that the oxidation index and rate constant of low-carbon MgO–C refractories with optimized Al3BC3–Al additions were 13% and 1.10 × 10−4 cm2 min−1 at 1400°C for 3 h, respectively, which is much lower than that of Al or Al3BC3 containing ones. Single Al3BC3 is not a suitable antioxidant for low-carbon MgO–C refractories; however, if Al3BC3 was initially protected and Al reacted as the antioxidant, enhanced oxidation resistance at high temperature can be achieved. The formation of dense MgO–MgAl2O4–Mg3B2O6 layer contributed to superior oxidation resistance, and the temperature for the generation of this layer was as low as 1100°C due to liquid and vapor phase–assisted reactions with Al3BC3–Al. Furthermore, a self-repairing function was achieved at 1600°C with the combination of Al3BC3–Al additions in spite of the faster oxidation rate. 相似文献
14.
Gengfu Liu Ning Liao Yawei Li Yang Zhang Zixu Ji Tianbin Zhu 《International Journal of Applied Ceramic Technology》2023,20(1):424-435
Al2O3–C refractories are potential candidates for use in gasifiers, and they are Cr2O3-free. However, the oxidation of the carbon species and ceramic phases within the high-temperature water vapor environment may deteriorate the integrity of the working lining. Ti3AlC2 has been verified as an effective antioxidant for Al2O3–C refractories in air. In this study, the structural transformation of Ti3AlC2 during heat treatment and the water vapor resistance of Ti3AlC2-containing Al2O3–C refractories are investigated. The results show that the oxidation of Ti3AlC2 and Si in the matrix contributes to the in situ formation of a multilayer core–shell structure of TiC–AlTi2O5–Al6Si2O13. These structural evolutions improve densification and stimulate pore size refinement, which enhances the mechanical properties and thermal stress resistance of the specimens. In particular, the refined pore size contributes to the significantly improved water vapor resistance at high temperatures. 相似文献
15.
《Journal of the European Ceramic Society》2003,23(6):927-934
Adding nickel inclusions into alumina can enhance its strength and toughness. However, the oxidation resistance of alumina is degraded due to the presence of metallic nickel. In the present study, the oxidation kinetics of Ni-toughened Al2O3 in the temperature region from 1000 to 1300 °C are investigated. In the Al2O3/Ni composites, the Ni inclusions are isolated to each other within the Al2O3 matrix as the Ni content is less than 15 vol.%. The oxidation of the composites is mainly a diffusional process, nickel ions diffuse out and oxygen ions diffuse in. A dense NiAl2O4 spinel is formed on the surface of the composite after oxidation. The oxidation rate constants of the alumina incorporated with isolated Ni inclusions are in a comparable range with those of hot-pressed silicon nitride. 相似文献
16.
《Ceramics International》2017,43(15):12126-12137
Mechanical resistance of Al2O3 + TiO2 nanocomposite ceramic coating deposited by electrostatic spray deposition method onto X10CrAlSi18 steel to thermal and slurry tests was investigated. The coating was produced from colloidal suspension of TiO2 nanoparticles dispersed in 3 wt% solution of Al2(NO3)3, as Al2O3 precursor, in ethanol. TiO2 nanoparticles of two sizes, 15 nm and 32 nm, were used in the experiments. After deposition, coatings were annealed at various temperatures, 300, 1000 and 1200 °C, and next exposed to cyclic thermal and slurry tests. Regardless of annealing temperature and the size of TiO2 nanoparticles, the outer layer of all coatings was porous. The first five thermal cycles caused a rapid increase of aluminum content of the surface layer to 30–37 wt%, but further increase in the number of thermal cycles did not affect the aluminum content. The oxidation rate of coating-substrate system was lower during the thermal tests than during annealing. The oxidation rate was also lower for smaller TiO2 particles (15 nm) forming the coating than for the larger ones (32 nm). The protective properties of Al2O3 + TiO2 coating against intense oxidation of substrate were lost at 1200 °C. Slurry tests showed that coatings annealed at 1000 °C had the best slurry resistance, but thermal tests had weakened this slurry resistance, mainly due to decreasing adhesion of the coating. 相似文献
17.
《Ceramics International》2023,49(7):10354-10359
One of the critical issues in the application of supercritical water oxidation technology is to improve the corrosion resistance of reactor materials. Use of Al2O3 coating is one of the most promising methods to address this issue. In this study, thick NiAl/Al2O3 coatings on Inconel 625 substrates were prepared by a consecutive pack embedding and in-situ thermal oxidation process. The effect of aluminizing and oxidation temperature on phase structure and coating thickness is studied. Results show the diffusion of Al from the exterior to the interior of the alloy matrix to form intermetallic compounds between Al and metal elements in the matrix (Ni, Cr, Mo, etc.). Moreover, the coating thickness can reach above 300 μm at the aluminizing temperature of 950 °C. Increasing the aluminizing temperature above 950 °C will not increase the coating thickness further. After high temperature oxidation subsequently, only phases of NiAl and Al2O3 were detected. The formation of Al2O3 layer can be ascribed to the surface oxidization of Al. And the NiAl between the alloy substrate and Al2O3 coating provides an interfacial layer that can alleviate the crack or exfoliation of ceramic coating due to the mismatching of thermal expand coefficient. The thick NiAl/Al2O3 coatings prepared by aluminizing 950 °C and oxidizing at 1100 °C exhibit satisfied corrosion resistance after supercritical water test. This work would provide a significant method to develop advanced ceramics coating for the corrosion resistance of alloys. 相似文献
18.
Junjie Song Hui Yang Raúl Bermejo Jianmin Qu Litian Hu Yongsheng Zhang 《Journal of the American Ceramic Society》2019,102(6):3673-3684
The use of ceramics such as alumina in moving components often requires the addition of low friction materials such as graphite. A new strategy for improving toughness, strength, and thermal-shock resistance of Al2O3–graphite self-lubricating composites was proposed in this study. Alumina layers embedded between Al2O3–graphite layers were fabricated and tested after thermal shock conditions ranging between 500 °C and 800 °C maximum temperature. Retained strength and apparent fracture toughness after the tests were compared to room temperature values. Results show that compressive residual stresses generated in the outer Al2O3–graphite layers during cooling down from sintering improve the failure resistance of the materials. The introduction of heat-resistant particles (Al2O3 particles) into graphite layers combined with a layered architecture can greatly decrease the oxidation degradation of the materials below 500 °C. In addition, the retained strength and toughness in the layered architectures after thermal shock between 550 °C and 800 °C remains constant, thus indicating that the new-developed Al2O3/Al2O3–graphite laminated composites may be reliable candidates for self–lubricating applications also for elevated temperatures. 相似文献
19.
《Ceramics International》2022,48(8):10911-10920
A novel MoSi2–Al2O3 composite coating was prepared on Mo-based TZM alloy by slurry sintering method. The oxidation behavior of the coating was evaluated at 1600 °C in static air. Microstructure and phase composition of the as-prepared and oxidized coatings were characterized, and the antioxidant mechanism of the coating at high temperature was discussed. A three-layer structure was observed in the as-prepared coating, consisting of a ~2 μm thick Mo5Si3 diffusion layer, a ~65 μm thick MoSi2 inner layer and a ~36 μm thick outer layer of mixture of MoSi2 and Al2O3. After oxidation at 1600 °C for 5 h, all MoSi2 phases were completely converted to intermediate silicide Mo5Si3 by solid-state diffusion, and the formed Mo5Si3 phase would be transformed into Mo3Si phase with further extending the oxidation time. Furthermore, a dense oxide layer of SiO2-mullite was formed on the specimen surface, which can effectively protect the material to further oxidation. The MoSi2–Al2O3 coating could protect the substrate effectively at 1600 °C for 20 h without failure. The enhanced oxidation resistance of MoSi2–Al2O3 coating is due to the formation of multi-layer structure containing a SiO2-mullite composite oxide outer layer with high thermal stability and low oxygen permeability. 相似文献
20.
《Ceramics International》2022,48(9):12184-12192
In this study, WC-15 wt% Al2O3 composites were prepared using the vacuum hot-pressing sintering method. The high-temperature (600–800 °C) oxidation behaviour of WC-15 wt% Al2O3 composites was investigated and compared with that of WC-6wt.%Co cemented carbides. The results showed that the oxidation resistance of WC-15 wt% Al2O3 composites was better than that of WC-6wt.%Co cemented carbides at relatively high temperatures (700–800 °C). At 800 °C, an oxide layer was formed on the surface of WC-15 wt% Al2O3 composites, which included WO3 and Al2O3. The dispersion of alumina in the composites hindered the further diffusion of oxygen, thus improving the oxidation resistance. The Arrhenius activation energies of WC-15 wt% Al2O3 composites and WC-6wt.%Co cemented carbides were 110 ± 1 kJ/mol and 167 ± 2 kJ/mol at 600–800 °C, respectively. 相似文献