Influence of annealing treatment on the microstructure and mechanical performance of cold sprayed 304 stainless steel coating

In this study, 304 stainless steel coatings were deposited on interstitial-free steel substrate by cold spraying method. The effect of annealing treatment on microstructure, microhardness, ultimate tensile strength and fracture performance of the coatings were studied. The results showed that annealing treatment had made a dominant contribution to heal up the incomplete interfaces between the deposited particles. Both of the microstructure and the mechanical properties have been obviously optimized by annealing treatment. In addition, the coating microhardness decreased from 345 HV_0.2 for the as-sprayed coating to 201 HV_0.2 for the annealed coating. The coating ultimate tensile strength increased from 65 MPa for the as-sprayed coating to 357 MPa for the annealed coating, which resulted from the increase of the metallurgically bonded areas in the coating induced by annealing treatment. Fracture morphology of the coatings also revealed that annealing treatment changed the fracture character of the cold sprayed 304 stainless steel coating from brittle type to plastic type.     

High temperature annealing effect on structural and magnetic properties of Ti/Ni multilayers

High temperature annealing effect on structural and magnetic properties of Ti/Ni multilayer (ML) up to 600 °C have been studied and reported in this paper. Ti/Ni multilayer samples having constant layer thicknesses of 50 Å each are deposited on float glass and Si(1 1 1) substrates using electron-beam evaporation technique under ultra-high vacuum (UHV) conditions at room temperatures. The micro-structural parameters and their evolution with temperature for as-deposited as well as annealed multilayer samples up to 600 °C in a step of 100 °C for 1 h are determined by using X-ray diffraction (XRD) and grazing incidence X-ray reflectivity techniques. The X-ray diffraction pattern recorded at 300 °C annealed multilayer sample shows interesting structural transformation (from crystalline to amorphous) because of the solid-state reaction (SSR) and subsequent re-crystallization at higher temperatures of annealing, particularly at ≥400 °C due to the formation of TiNi₃ and Ti₂Ni alloy phases. Sample quality and surface morphology are examined by using atomic force microscopy (AFM) technique for both as-deposited as well as annealed multilayer samples. In addition to this, a temperature dependent dc resistivity measurement is also used to study the structural transformation and subsequent alloy phase formation due to annealing treatment. The corresponding magnetization behavior of multilayer samples after each stage of annealing has been investigated by using Magneto-Optical Kerr Effect (MOKE) technique and results are interpreted in terms of observed micro-structural changes.     

Influence of annealing temperature on the structural, optical and mechanical properties of ALD-derived ZnO thin films

ZnO thin films grown on Si(1 1 1) substrates by using atomic layer deposition (ALD) were annealed at the temperatures ranging from 300 to 500 °C. The X-ray diffraction (XRD) results show that the annealed ZnO thin films are highly (0 0 2)-oriented, indicating a well ordered microstructure. The film surface examined by the atomic force microscopy (AFM), however, indicated that the roughness increases with increasing annealing temperature. The photoluminescence (PL) spectrum showed that the intensity of UV emission was strongest for films annealed at 500 °C. The mechanical properties of the resultant ZnO thin films investigated by nanoindentation reveal that the hardness decreases from 9.2 GPa to 7.2 GPa for films annealed at 300 °C and 500 °C, respectively. On the other hand, the Young's modulus for the former is 168.6 GPa as compared to a value of 139.5 GPa for the latter. Moreover, the relationship between the hardness and film grain size appear to follow closely with the Hall-Petch equation.     

退火对钛/铜热等静压扩散连接界面的影响

钛/铜(Ti/Cu)作为ITER 第一壁Be/CuCrZr 热等静压连接中间过渡层,形成了多层中间金属相结构,容易在Ti/Cu 金属相之间产生裂纹等缺陷。采用CuCrZr 代替Be,经过与Be/CuCrZr 相同的热等静压工艺,制作了多个CuCrZr/Ti/Cu/CuCrZr 连接件,对Ti/Cu 连接接头进行深入分析。对连接件分别进行未退火、400℃和500℃ 退火处理,去应力退火后对接头强度和缺陷分布的影响进行了研究。研究结果表明,中间钛层的两侧都形成了三层Ti/Cu 扩散层,分别为Cu₄Ti、CuTi 和CuTi₂。纯铜侧的Cu₄Ti 厚度比CuCrZr 侧的厚,使得裂纹几乎全部分布于铜侧的Cu₄Ti 与CuTi 交界处,拉伸样品极易在此处发生脆性断裂。随着退火温度升高,裂纹的产生和扩展减少。     

Characterization of silane layers on modified stainless steel surfaces and related stainless steel-plastic hybrids

The aim of this work was to characterize silane layers on the modified stainless steel surfaces and relate it to the adhesion in the injection-molded thermoplastic urethane-stainless steel hybrids. The silane layers were characterized with scanning electron microscope and transmission electron microscope, allowing the direct quantization of silane layer thickness and its variation. The surface topographies were characterized with atomic force microscope and chemical analyses were performed with X-ray photoelectron spectroscopy. The mechanical strength of the respective stainless steel-thermoplastic urethane hybrids was determined by peel test. Polishing and oxidation treatment of the steel surface improved the silane layer uniformity compared to the industrially pickled surface and increased the adhesion strength of the hybrids, resulting mainly cohesive failure in TPU. XPS analysis indicated that the improved silane bonding to the modified steel surface was due to clean Fe₂O₃-type surface oxide and stronger interaction with TPU was due to more amino species on the silane layer surface compared to the cleaned, industrially pickled surface. Silane layer thickness affected failure type of the hybrids, with a thick silane layer the hybrids failed mainly in the silane layer and with a thinner layer cohesively in plastic.     

Characterization of the oxides formed at 1000 °C on the AISI 304 stainless steel by X-ray diffraction and infrared spectroscopy

The aim of this work is to show the contribution of the infrared spectroscopy (FT-IR) to the identification of the oxides formed on the AISI 304 stainless steel during isothermal oxidation at 1000 °C, in air. This work focuses on the differentiation of spinel type AB₂O₄ structures and corundum type M₂O₃ structures. It is shown that after 100 h oxidation, the scale is composed of two subscales. The structural analyses were performed both on the adherent subscale and on the external subscale, which spalled off during cooling to room temperature. In the spalled subscale, the infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analyses exhibit the presence of two spinel phases: Mn_1.5Cr_1.5O₄ and FeCr₂O₄, as well as hematite Fe₂O₃. The FT-IR and XRD analyses of the adherent subscale enable us to distinguish the spinel Mn_1.5Cr_1.5O₄ and FeCr₂O₄ structures which are difficult to identify by XRD alone. Chromia Cr₂O₃ appears to be slightly present in the adherent subscale. According to our results, the parabolic regime of the kinetic curve corresponds to a scale growth mechanism governed by an inward oxygen diffusion.     

Structural properties of TiN films grown on stainless steel substrates by a reactive radio-frequency sputtering technique at low temperature

TiN thin films were grown on stainless steel substrates by using the reactive radio-frequency magnetron-sputtering technique at relatively low temperature (200°C) using Ti and N₂. The deposition rate of the TiN film increased linearly with increasing applied radio-frequency power, and it decreased with increasing partial-pressure ratio of the N₂ gas to the Ar gas. Scanning electron microscopy (SEM) showed that the surfaces of the TiN films had very smooth morphologies. The TiN thin film had good stoichiometry for a partial-pressure ratio of 0.05. The stoichiometry of the TiN films and the interface qualities of the TiN/stainless steel heterostructures were investigated by Auger electron spectroscopy (AES) measurements. Auger depth profiles indicated that the compositions of the as-grown films consisted of titanium and nitrogen uniformly distributed throughout the films and that the films exhibited smooth interfaces. The interface quality of the TiN films to the stainless steel substrates were improved by annealing. These results indicate that annealed TiN thin films grown on stainless steel substrates hold promise for potential applications in advanced ceramic devices.     

The effect of deposition temperature on the surface coverage and morphology of iron-phosphate coatings on low carbon steel

The influence of deposition temperature and concentration of NaNO₂ in the phosphating bath on the surface morphology and coverage of iron-phosphate coatings on low carbon steel was investigated. The phosphate coatings were chemically deposited on steel from phosphate bath at different temperatures (30-70 °C) and with the addition of different amounts of accelerator, NaNO₂ (0.1, 0.5 and 1.0 g dm⁻³). The morphology of phosphate coatings was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The composition of iron-phosphate coatings was determined using energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Surface coverage was evaluated by the voltammetric anodic dissolution (VAD) technique.It was shown that the increase in temperature of the NaNO₂-free phosphating bath up to 70 °C caused an increase in surface coverage. The addition of NaNO₂ in the phosphating bath significantly increased the surface coverage of phosphate coatings deposited at temperatures lower than 50 °C. The phosphate crystals were of laminated and needle-like structures for deposits obtained at temperatures lower than 50 °C, while at higher temperatures needle-like structure was transformed to laminated structure. The increase in NaNO₂ concentration in the phosphating bath from 0.1 to 1.0 g dm⁻³ did not significantly increase the surface coverage, but decreased the crystals size, consequently favouring the phosphate nucleation and better packing of the crystals.     

强流脉冲离子束辐照对不锈钢耐腐蚀性能的影响

 利用强流脉冲离子束（HIPIB）对316L不锈钢进行了表面辐照处理,研究了HIPIB辐照对其在0.5mol/L H2SO4溶液中电化学腐蚀性能的影响。极化曲线测量结果表明,HIPIB辐照能够显著提高316L的抗腐蚀性能,自腐蚀电流对辐照次数的依赖性与自腐蚀电位相比明显较强。采用扫描电子显微镜（SEM）、X射线衍射（XRD）和电子探针（EPMA）分析辐照后试样表面形貌、表面层相结构和元素分布的变化。结果表明：HIPIB辐照使试样表面光滑化,表面层产生择优取向,且发生了杂质元素的选择性烧蚀,是316L不锈钢耐电化学腐蚀性能得以提高的主要原因。     

Influence of Ni deposition and subsequent N ion implantation at different substrate temperatures on nano-structure and corrosion behaviour of type 316 and 304 stainless steels

Ni thin films of 250 nm thicknesses were coated on type 304 and 316 stainless steels and post N⁺ ion implanted at 15 keV energy with a fluence of 5 × 10¹⁷ N⁺ cm⁻² at different substrate temperatures. Surface nano-structure of the samples were analysed using X-ray diffraction (XRD), atomic force microscopy (AFM) before corrosion test and scanning electron microscopy (SEM) after corrosion test. Corrosion behaviour of the samples in 1.0 M H₂SO₄ solution was investigated by means of potentiodynamic technique. Nano-structure and crystallography of the films showed the development of Ni₃N(1 1 1) and Ni₄N(2 0 0) orientations with a minimum surface roughness and grain size at 400 K substrate temperature. The highest corrosion resistance with a corrosion current of 0.01 μA cm⁻² (for SS(316)) and 0.56 μA cm⁻² (for SS(304)) was achieved in case of samples which were N⁺ ion implanted at 400 K. Results for both types of stainless steels showed good agreement and the better performance of SS(316) was attributed to the 2% molybdenum contents in the alloy composition of this type of stainless steel, which enhances the effectiveness of nitrogen in retarding the corrosion process.     

Effects of aging temperature on G-phase precipitation and ferrite-phase decomposition in duplex stainless steel

G-phase precipitation and ferrite-phase decomposition in a cast duplex stainless steel (DSS) aged at 623–723?K for up to 8000?h were investigated using atom probe tomography (APT). Large sample volume was observed in every APT experiment, which yielded significantly statistical results. The number density of G-phase precipitates tended to be high and their sizes were small at lower aging temperatures. G-phase precipitates grew during prolonged isothermal aging. The concentrations of nickel, silicon, manganese and molybdenum in G-phase precipitates tended to increase as the precipitates grew. Heterogeneous distributions of alloying elements within G-phase precipitates were observed. An interesting positional relationship of G-phase precipitates with dislocations was revealed. Regarding the ferrite-phase decomposition, local chromium concentrations in the ferrite phase varied fast at higher aging temperatures. Good correlation between the variation of local chromium concentrations and aging conditions was revealed, which indicates that the variation can be estimated for arbitrary aging conditions. Representative distances between chromium-enriched and chromium-diluted regions were long at higher aging temperatures. Time exponent of the representative distances of ferrite-phase decomposition as well as the size of G-phase precipitates increased with aging temperatures.     

强流脉冲离子束辐照对不锈钢耐腐蚀性能的影响

利用强流脉冲离子束（HIPIB）对316L不锈钢进行了表面辐照处理,研究了HIPIB辐照对其在0.5mol/L H2SO4溶液中电化学腐蚀性能的影响。极化曲线测量结果表明,HIPIB辐照能够显著提高316L的抗腐蚀性能,自腐蚀电流对辐照次数的依赖性与自腐蚀电位相比明显较强。采用扫描电子显微镜（SEM）、X射线衍射（XRD）和电子探针（EPMA）分析辐照后试样表面形貌、表面层相结构和元素分布的变化。结果表明：HIPIB辐照使试样表面光滑化,表面层产生择优取向,且发生了杂质元素的选择性烧蚀,是316L不锈钢耐电化学腐蚀性能得以提高的主要原因。     

退火温度对溅射铝膜结构与电性能的影响

 采用直流磁控溅射方法成功地制备了Al膜,研究了退火温度对Al膜表面形貌、晶体结构、应力、择优取向及反射率的影响。研究表明：不同退火温度的薄膜晶粒排布致密而光滑,均方根粗糙度小。XRD测试表明：不同温度退火的铝膜均成多晶状态,晶体结构为面心立方,退火温度升高到400 ℃时,Al膜的应力最小达0.78 GPa,薄膜平均晶粒尺寸由18.3 nm增加到25.9 nm;随着退火温度的升高,(200)晶面择优取向特性变好。薄膜紫外-红外反射率随着退火温度的升高而增大。     

Influence of treating frequency on microstructure and properties of Al2O3 coating on 304 stainless steel by cathodic plasma electrolytic deposition

Alumina ceramic coatings were fabricated on 304 stainless steel by cathodic plasma electrolytic deposition (CPED). Influence of treating frequency of the power supply on the microstructure and properties of the coatings were studied. The results indicated that coatings obtained at various frequencies on 304 stainless steels were all composed of α-Al₂O₃ and γ-Al₂O₃, and α-Al₂O₃ was the dominant phase. The contents of α-Al₂O₃ decreased gradually in a very small rate with increasing the frequency and γ-Al₂O₃ gradually increased. The surface of alumina ceramic coating was porous. With increasing the frequency, the coating surface gradually became less rough and more compact, resulting in low surface roughness. The bonding strength of Al₂O₃ coating was higher than 22 MPa and was not strongly affected by treating frequency. With increasing the frequency, the alumina coated steels showed better and gradually increasing corrosion resistance than the uncoated one in 3.5% NaCl solution. The coating steel with desirable corrosion resistance was obtained at 800 Hz whose corrosion current potential and corrosion density were −0.237 V and 7.367 × 10⁻⁸ A/cm², respectively.     

Structural and electrical characterization of the nickel silicide films formed at 850 °C by rapid thermal annealing of the Ni/Si(1 0 0) films

Nickel di-silicide formation induced by RTA process at 850 °C for 60 s in the Ni/Si(1 0 0) systems are investigated as a function of the initial Ni film thickness of 7-89 nm using XRD, RBS, SEM, X-SEM and AFM. Based on the XRD and RBS data, in the silicide films of 400-105 nm, NiSi and NiSi₂ silicide phases co-exist, indicating that Ni overlayer is completely transformed to NiSi and NiSi₂ silicide phases. SEM reveals that these films consist of large grains for co-existence of NiSi₂ and NiSi phases, separated from one another by holes, reflecting that NiSi₂ grows as islands in NiSi matrix. These films have low sheet resistance, ranging from 1.89 to 5.44 Ω/□ and good thermal stability. For thicknesses ≤ 80 nm RBS yields more Si-rich silicide phases compared to thicker films, whereas SEM reveals that Si-enriched silicide islands with visible holes grow in Si matrix. As the film thickness decreases from 400 to 35 nm, AFM reveals a ridge-like structure showing a general trend of decreasing average diameter and mean roughness values, while sheet resistance measurements exhibit a dramatic increase ranging from 1.89 to 53.73 Ω/□. This dramatic sheet resistance increase is generated by substantial grain boundary grooving, followed by island formation, resulting in a significant phase transformation from NiSi₂-rich to Si-rich silicide phases.     

Thermally oxidised rutile-TiO2 coating on stainless steel for tribological properties and corrosion resistance enhancement

In the present work, a novel process has been developed to improve the tribological and corrosion properties of austenitic stainless steels. Efforts have been made to deposit titanium coatings onto AISI 316L stainless steel by magnetron sputtering, and then to partially convert the titanium coatings to titanium oxide by thermal oxidation. The resultant coating has a layered structure, comprising of rutile-TiO₂ layer at the top, an oxygen and nitrogen dissolved α-Ti layer in the middle and a diffuse-type interface. Such a hybrid coating system showed good adhesion with the substrate, improved corrosion resistance, and significantly enhanced surface hardness and tribological properties of the stainless steel in terms of much reduced friction coefficient and increased wear resistance.     

Laser irradiation of AISI 316L stainless steel coated with Si3N4 and Ti

AISI 316L stainless steel was laser surface treated with different compositions of Si₃N₄ and Ti under various laser-processing parameters to improve its surface hardness through reinforcement of Ti-based silicides. The laser-treated regions exhibited improved surface hardness (250–1000 HV), variations in the surface morphology (smooth and bowl like) and presence of cracks and pores depending upon the Si₃N₄–Ti composition and laser-processing parameters. The study shows that when the Si₃N₄–Ti composition is 75–25 wt% and laser parameters are 1.5 kW laser power and 1.0 m min⁻¹ scan speed, a laser-treated region with high hardness of about 800 HV and smooth surface morphology as well as free from pores and cracks is observed. The X-ray diffractometer (XRD) and Energy-Dispersive Spectroscopy (EDS) analyses show that the laser surface-treated region has reinforced phase of Ti₅Si₃ and retained austenitic structure. The reinforced phase gives rise to very high hardness (or wear resistance) and also a corrosion resistance.     

退火时间对MgB_2超导薄膜的影响

在多晶A l2O3衬底上,以B2H6作为硼源,化学气相沉积先驱B薄膜,采用Mg扩散方法,在不同退火时间条件下制备了MgB2超导薄膜。通过电阻-温度曲线测量、X射线衍射分析和扫描电子显微镜形貌观测方法,研究了退火时间对MgB2薄膜的超导特性、晶体结构、表面形貌的影响。     

Study of the MOCVD growth of ZnO on GaAs substrates: Influence of the molar ratio of the precursors on structural and morphological properties

ZnO thin films were grown by metal-organic chemical vapour deposition (MOCVD) on GaAs(100) and GaAs(111)A substrates. The growth experiments were performed at temperatures ranging from 290 to 500 C and atmospheric pressure. Diethylzinc (DEZn) and tertiary butanol (tBuOH) were used as Zn and O precursors, respectively. The crystallinity of the grown films was studied by X-Ray Diffraction (XRD) and the thickness and morphology were investigated by Scanning Electron Microscopy (SEM). The influence of substrate orientation and molar ratio of the precursors on the crystalline orientation and morphology of the ZnO grown films was analysed.     

B掺杂对Ti薄膜结构与性能的影响

采用双靶共溅射方法制备了微量B掺杂的Ti薄膜样品, 利用X射线光电子能谱、扫描电子显微镜和X射线衍射仪对样品的掺杂原子浓度、 表面形貌、晶型结构、晶粒尺寸和应力进行了分析表征. 研究表明: 掺杂后的Ti薄膜晶粒得到明显细化, 并随着掺杂浓度的增大, 薄膜的晶粒尺寸呈减小趋势, 当掺杂浓度为5.50 at%时, Ti薄膜晶粒尺寸减小为1.3 nm, 呈现出致密的柱状结构. B掺杂后的Ti薄膜应力由压应力转变为张应力.