APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Mohammadreza Rostami,Biao Yang,Felix Haag,Francesco Allegretti,Lifeng Chi,Martin Stutzmann,Johannes V. Barth
Gallium nitride (GaN), a wide bandgap semiconductor with absorption and emission in the ultraviolet/visible range, is proposed as an alternative to metallic surfaces for assembling organic molecular structures aiming at optoelectronic applications. However, the formation of a persistent surface oxide layer in air considerably limits the use of GaN for well-defined interfaces. In this work, we have investigated, characterized and processed n-type free-standing c-plane hexagonal wurtzite GaN crystals grown by hydride vapor phase epitaxy and ammonothermal growth methods. Surface cleaning and full removal of the oxide layer on GaN surfaces could be reproducibly achieved via sputtering and annealing cycles, as evidenced by X-ray photoelectron spectroscopy and low-energy electron diffraction. Scanning tunneling microscopy, however, indicated substantial roughening of the GaN surface and the formation of unwanted Ga-rich islands and clusters. Although ammonia (NH 3 ) and bromine (Br) treatments compensated the N/Ga atoms ratio reduced by sputtering, the surface morphology remained rough, exhibiting randomly shaped and distributed hillocks. In addition, we studied the effect of electron bombardment on the surface quality of GaN during NH 3 annealing, on-surface debromination and polymerization of 1,3,5-tris(4-bromophenyl) benzene on GaN, and the removal of Ga atoms by Br atoms during the desorption.
研究领域:
材料科学
·
表面科学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
Yina Du,Ji-Xuan Liu,Yifeng Gu,Xin-Gang Wang,Fangfang Xu,Guo-Jun Zhang
Textured and untextured M n+1 AX n compounds, Ti 2 AlC and Ti 3 AlC 2 , namely MAX phases have been synthesized and examined with respect to their corrosion resistance in static supercritical water at 500 °C. The textured ceramics were obtained by hot forging process at high temperatures. Both X-ray diffraction and SEM analysis revealed well alignment of c -plane of MAX phases parallel to the hot-forging surface. Better corrosion resistance on the surface perpendicular to the hot-forged direction was verified by SEM. On the other hand, the side surfaces of the samples showed thick oxidation layers and abundant cracks. The (00 l ) faces consist of strongly bonded Ti 3 C 2 and Ti 2 C layers in Ti 3 AlC 2 and Ti 2 AlC, respectively, hence exhibit higher resistance to water corrosion. On the contrary, the side surfaces where most of weakly bonded interlayers of these hexagonal phases were exposed tend to be easily corroded especially through Al-layers. The corrosion process involved a phase transition of oxidized product, i.e. TiO 2 from anatase to rutile phase, which gave rise to the formation of cracks due to accompanied volume changes.
研究领域:
材料科学
·
腐蚀工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Wenhao Dou,Daxin Li,Bingzhu Wang,Zhihua Yang,Dechang Jia,Ralf Riedel,Yu Zhou
The microstructural evolution of C sf /SiBCN composites and formation mechanism of the oxide layer after oxidation for 1–10 h at 1500 ℃ were studied. As the oxidation time increases to 10 h, the macrostructure of the porous C sf /MA-SiBCN composite collapses obviously, while the C sf /SiBCN composite densified via the polymer infiltration and pyrolysis (PIP) process maintains structural integrity due to the formation of the oxide layer with a tri-layer structure: the outermost loose layer mainly containing cristobalite, the dense interlayer of amorphous glass and the innermost layer of some unoxidized BN(C) and SiC grains embedded into the amorphous glass, which hinders the diffusion of oxygen.
研究领域:
材料科学
·
复合材料
·
氧化行为
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2023
·
IF 4.4
Longfei Yun,Yanan Wang,Baozhong Zhu,Yunlan Sun
Aluminum (Al) powder is easy to agglomerate in the combustion process , thereby inhibiting its continuous combustion, which results in the reduction of combustion intensity and combustion efficiency directly. Polyacrylamide (PAM), as a high molecular weight polymer , has the potentiality to react with Al via many aromatic compounds produced from its cracking. In this study, a solvent/non-solvent method was used to successfully coat micron-sized Al particles with PAM to form the PAM@μAl, aiming to improve their ignition and combustion properties . The results show that PAM and μAl interact in the PAM@μAl samples, and PAM inhibits the generation of oxide layer on the Al surface during the combustion process, while the presence of Al affects the thermal behavior of PAM. The combustion process of the PAM@μAl samples includes three stages: explosive combustion, transitional combustion, and stable combustion. Compared with the monolithic Al, the PAM@μAl samples have a shorter ignition delay and greater combustion intensity, and the oxide shell on the surface of Al particles is more easily broken, which is beneficial to the internal molten Al overflow. In addition, PAM can effectively inhibit the agglomeration behavior between Al particles during the combustion process. In particular, the best ignition and combustion performance of the PAM@μAl samples appears when the mass percentage of PAM is 7 wt.%.
研究领域:
材料科学
·
燃烧与热能工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 21
·10669-10677
·
IF 8.867
Lian-Kui Wu,Wei-Yao Wu,Jie Xia,Hua-Zhen Cao,Guang-Ya Hou,Yi-Ping Tang,Guo-Qu Zheng
A nanostructured nickel–cobalt alloy with an oxide layer was fabricated and its superior catalytic activity towards the electrochemical oxygen evolution reaction in alkaline media was investigated. Firstly, a NiCo–SiO2 composite film was prepared via a potentiostatic electro-codeposition method. Then the SiO2 template was etched and the NiCo component was activated leading to the generation of a NiCoOx layer during consecutive CV scans in concentrated alkaline solution. The results show that this nanostructured NiCo alloy with the oxide layer can provide a current density of 100 mA cm−2 in 1.0 M KOH at a low overpotential of 326 mV and exhibits good stability towards water oxidation. The excellent OER performance is enabled with the unique metal-oxide structure, which allows high electrical conductivity in the metal and high catalytic activity on the oxide.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Chao Yang,Zhijian Zhang,Zhongliang Tian,Yanqing Lai,Kai Zhang,Jie Li
Two anodized-layer structures of zinc in alkaline solution were obtained by different anodic polarizations in 6 M KOH, which contained different carboxymethyl cellulose (CMC) molecular weights (MWs). The electrochemical characteristics and electrodeposition behaviors of the oxide layers, which were obtained before and after passivation, were investigated. Results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Tafel polarization curves and zinc deposition indicated that different CMC MWs showed opposite effects on the porous oxide layer and passive film. Scanning electron microscopy analyses revealed that CMC with different characteristics can influence the surface structures of the porous oxide layer and passive film.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2023
·
IF 10.9
Pu Zhao,Zhengwei Li,Zhiwu Xu,Xuesong Leng,Anqi Tong,Jiuchun Yan
The oxide layer on the surface has always been a key obstacle to achieving the diffusion bonding of Al alloys. It is a challenge for performing diffusion bonding without removing oxide layers. Herein, diffusion bonding of Al alloy retaining continuous oxide layers was successfully achieved in the air by a low-temperature and low-pressure diffusion bonding mothed using a Zn interlayer. During the bonding processes, conducted at 360 °C and 3 MPa, Zn diffused into Al through cracks of thin oxide layers to form the joint composed Al/(diffusion layer)/(oxide layer)/(Zn)/(oxide layer)/(diffusion layer)/Al. The diffusion layers were composed of Zn-Al eutectoid, and the oxide layer included nanocrystals and amorphous Al 2 O 3 . The shear strength of joints containing continuous oxide layers was about 30 MPa. Interestingly, the migration behavior toward the joint center of the interfacial oxide layers was observed with consuming of the Zn interlayer. The cracking phenomenon, the “subcutaneous diffusion” and the migration behavior of oxide layers were verified and analyzed by the diffusion bonding of anodized 6063Al-6063Al. Subsequently, the dynamic migration mechanism of oxide layers with elements diffusion and bonding interface strengths were discussed in detail. The ability to join Al alloys in the air at low temperatures and low pressure suggests a highly practical and economic method for diffusion bonding.
研究领域:
材料科学
·
冶金工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL SPRAY TECHNOLOGY
·
2023
·Vol. 32
·期 8
·2460-2477
·
IF 3.1
Wu Duoli,Wu Haotian,Yuan Ziyi,Wei Xinlong,Zhang Chao
To investigate the influence of Mo addition and water vapor content on the high-temperature corrosion resistance of Ni-Al-based coatings, 0Mo, 5Mo, and 10Mo coatings were deposited by APS thermal spray onto stainless steels. The chlorine-induced corrosion test was conducted in an experimental environment simulating a biomass boiler. The results show that adding the Mo element lowers the coating's ability to resist corrosion without water vapor. The coating is more prone to peeling because Mo prevents the coating from eventually forming a protective oxide layer. Water vapor significantly speeds up the production of oxides and modifies their morphology and structure. The combined effects of Mo and water vapor increase the coating's ability to resist corrosion. The development of thick and protective Ni and Al oxide layers on the coated surface is aided by the acceleration of oxide production by water vapor and the alteration of oxide structure by Mo components.
研究领域:
材料科学
·
腐蚀与防护
✓ 已验证
产品关联
DOI
高影响因子
Science China-Materials
·
2024
·
IF 6.8
Zhang Baichao,Cao Xuchuan,Suo Chao,Cui Jing,Duan Xiaochuan,Guo Shaohui,Zhang Xian-Ming
Utilizing plasmonic non-noble metal nanoparticles (NPs) for photocatalytic hydrogen evolution reaction is a significant step toward green energy production. However, optimizing the interface between non-noble metal NPs and semiconducting materials in metal-semiconductor composites remains challenging owing to the inevitable surface oxide layers of non-noble metal NPs because the surface oxide layers of non-noble metal NPs can suppress the transfer of photoinduced carriers, leading to poor photocatalytic performance. Herein, we propose a photoinduced interface activation strategy to reduce the number of oxide layers based on a dynamic charge-transfer mechanism under illumination conditions, with Bi NPs and a Ni-based metal-organic framework (MOF) selected as model materials. Under light illumination, the photoinduced charges and plasmonic hot electrons heavily pooled at the interface between the Bi NPs and Ni-MOF, resulting in the reduction of the oxide layer on the surface of Bi, thus attenuating its hindering effect on charge transfer. This phenomenon led to a dynamically enhanced carrier concentration in the Bi/Ni-MOF composite, with an outstanding photocatalytic hydrogen evolution rate of 5822 µmol g −1 h −1 achieved with the composite. The results of this study indicate that our strategy provides a new method for optimizing plasmonic non-noble metal Bi NPs with oxide layers.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2022
·
IF 6.364
Qiankun Xu,Qingliang Shan,Jianbao Hu,Yewei Wang,Yu Wang,Qian Ma,Changrong Chen,Yuqian Zhou,Anze Shui
The oxidation property of SiC-B 4 C- x Al 2 O 3 ( x ranges from 0 wt% to 30 wt%) ceramics was studied in air at 1400 ℃. Results show that the porous oxide layer becomes dense and smooth with addition of Al 2 O 3 . When the content of Al 2 O 3 is proper, the DOP (degree of polymerization) of borosilicate network can be improved with increase of Al 2 O 3 content, inhibiting the migration of atoms and molecular groups. With that, the crystallization of SiO 2 and volatilization of B 2 O 3 can be restrained. When the content of Al 2 O 3 is excessive, the DOP of borosilicate network will be decreased, deteriorating the oxide layer morphology. It is believed that the damage of borosilicate network by excess Al 2 O 3 should be responsible for this phenomenon. In this research, the SiC-B 4 C ceramic with optimal oxidation resistant can be obtained when the content of Al 2 O 3 is 15 wt%.
研究领域:
材料科学
·
无机非金属材料
·
高温材料
·
表面工程
·
陶瓷学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Jiao Li,Jian Zhang,Yulin Yang,Kaifeng Lin,Debin Xia
The oxide layer on the Al particle surface seriously limits application in solid propellants, resulting in low combustion efficiency. This work prepares a series of Al decorated by nano-silver (namely Al/Ag) via in-situ reduction to enhance combustion performance Thanks to silver’s smaller specific heat capacity, surplus heat energy is transferred to the Al core through a tight combination with decorated noble metal nanoparticles. Along with the intermetallic reaction, the thermal stress on Al would accelerate the oxide shell rupture to reduce the oxygen gas diffusion barrier during combustion. The oxidation temperature of Al/Ag-2 composites decreases from 1017.3 °C to 982.93 °C. Hence, the combustion performance of solid propellants containing Al/Ag composites is improved with the higher maximum flame temperature and emission spectra intensity. In addition, the thermal decomposition of ammonium perchlorate (AP) is catalyzed via nano-silver. The combustion efficiency of the propellant containing Al/Ag-2 is effectively improved by the synergistic effect in which the potential energy from Al and AP is exploited as far as possible. This work demonstrates that metal surface modification significantly improves the combustion performance of solid propellants.
研究领域:
材料科学
·
燃烧与推进
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Ruoyu Chen,Hongbin An,Jie Zhan,Saisai Li,Aiqin Mao,Haiming Wen
A high entropy carbide (TaNbTiV)C was fabricated via spark plasma sintering of high entropy powders that were prepared using a molten salt method. The as-fabricated high entropy carbide was then investigated for its high-temperature oxidation behavior at 850 °C, under atmospheres with three different oxygen contents (20 vol%, 40 vol%, and 60 vol%). After the high-temperature oxidation process, the main phases observed in all the specimens were incompletely oxidized phase (Nb x Ti 1-x )C y O 2-y and oxides (Nb 0.5 Ta 0.5 ) 2 O 5 , TiO 2 , and Nb 2 O 5 . Importantly, the thickness of the oxide layer initially increased and then decreased as the oxygen content increased. When the oxygen content reached 40 vol%, the ceramic displayed severe oxidation behavior with observed thicker of the oxide layer, as well as numerous pores and cracks in the oxide layer. This work provides new insights into the oxidation behavior of high entropy carbides.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）