Substrate Heat Treatment Research Articles

A Substrate-Integrated and Scalable Templated Approach Based on Rusted Steel for the Fabrication of Polypyrrole Nanotube Arrays

We report here a facile, generalizable, and entirely scalable approach for the fabrication of vertically aligned arrays of Fe(2)O(3)/polypyrrole core-shell nanostructures and polypyrrole nanotubes. Our "all electrochemical" approach is based on the fabrication of α-Fe(2)O(3) nanowire arrays by the simple heat treatment of commodity low carbon steel substrates, followed by electropolymerization of conformal polypyrrole sheaths around the nanowires. Subsequently, electrochemical etching of the nanowires yields large-area vertically aligned polypyrrole nanotube arrays on the steel substrate. The developed methodology is generalizable to functionalized pyrrole monomers and represents a significant practical advance of relevance to the technological implementation of conjugated polymer nanostructures in electrochromics, electrochemical energy storage, and sensing.

Investigation of the structure and magnetic and mechanical properties of textured substrates of an Ni-Cr-W alloy

Based on the data of X-ray diffraction, electron-backscatter diffraction, dilatometry, thermal analysis, and scanning electron microscopy, we determined the optimum regimes of heat treatment of cold-rolled tape substrates of an alloy Ni88.4Cr9.2W2.4 that permit obtaining a perfect cube texture. It has been shown that the use of two-stage annealings makes it possible to obtain in this ternary nickel alloy a cube texture in which the scatter about the rolling direction (RD) and the transverse direction (TD) of the substrates varied within 6.75°–7.20° and 4.8°–5.4°, respectively.

Nanogenerators Based on ZnO or TiO<SUB>2</SUB> Oxides

Recently, an approach for converting nanoscale mechanical energy into electrical energy has been suggested by using piezoelectric zinc oxide (ZnO) nanowire arrays. Such devices have been shown to convert ultrasonic energy into electric energy by a deflection of the nanowires via a corrugated electrode operated up and down by the ultrasound. A typical approximately 1 pW output power for a device of a approximately 1 mm2 area and a density of approximately 10(7)/mm2 nanowires can be obtained. In order to reach the approximately 10 nW power needed to operate a nanodevice, nanogenerators of this kind need to be optimized. With the aim of fabricating low cost to efficiency ratio nanogenerators, we have considered ZnO films grown by an electrochemical technique, based on the direct precipitation of Zn hydroxide on a conducting ITO/glass substrate and subsequent heat treatment, and TiO2 films deposited from a colloidal suspension of anatase/rutile commercial powders. These methods allowed us to obtain disordered but quite uniform arrays distributed on the surface of the substrate. Preliminary results on the electrical properties are presented. Under input mechanical strain we find output powers of approximately 10(-9)/cm2 W, which are comparable to those obtained with the ZnO nanoarrays. Possible interpretations of results in terms of piezoelectricity (ZnO) and incipient ferroelectricity (TiO2) are presented and improvements of the devices are discussed.

Heat treatment of electrospun silicate fiber substrates enhances cellular adhesion and proliferation

Synthetic scaffolds support cell attachment in vitro. We prepared ultra-fine silicate fibers using the sol-gel process and electrospinning, heated the fibers to 500 degrees C and investigated their effects on the behavior of human hepatocellular carcinoma (HepG2) cells. Alterations in surface composition following heat treatment improved cell adhesion and influenced cell migration.

Growth of ZnO Nanowires Using ZnS Substrates with Ga Droplets

ZnO nanowires were synthesized by the heat treatment of ZnS substrates with Ga droplets in the air, and their morphological and structural properties were then investigated. The nano-sized ZnO wires were formed on thin ZnO layers accompanied with the formation of ZnGa2O4. It was found that the growth direction of the nanowires is ZnO[0001], and which is parallel to ZnGa2O4[010]. The growth mechanism of the ZnO nanowires is discussed based on the thermal stability or enthalpy of formation of the oxides. [DOI: 10.1380/ejssnt.2009.25]

Effect of substrate heat treatment on morphology and corrosion resistance of Zn–Mn phosphate coating

Phosphate coatings are one of the ancient methods for improvement the corrosion resistance of steels. Many researchers have investigated the effect of process parameters on the structure and properties of these coatings, but the influence of substrate microstructure has been less studied. In this article, the effect of heat treatment of AISI 4130 steel on the surface morphology and corrosion resistance of Zn–Mn phosphate coating has been investigated. The steel substrate was subjected to different heat treatments before coating application. X-ray diffraction, optical and scanning electron microscopy were used for phase and microstructure analysis respectively. The corrosion resistance of the coatings was studied by means of salt spray, potentiodynamic polarisation and electrochemical impedance spectroscopy methods. The results showed that the corrosion resistance of phosphate coatings is greatly influenced by substrate microstructure. The finer the steel microstructure, the more condensed becomes the coating morphology and the better its corrosion resistance.

Post-treatment of thermal spray coatings on magnesium

Magnesium alloys have a beneficial combination of high strength to weight ratio, good machinability and high recycling potential. Despite this, the application of magnesium still is behind that of other constructive materials mainly due to low wear and corrosion resistance. For more demanding applications, a large amount of surface treatment methods are developed to overcome this problem. Thermal spraying is an efficient and flexible method of coating deposition and is widely used for protection of different materials against corrosion and wear. Nevertheless, the bonding of thermal spray coatings on magnesium alloys is not sufficient, so the following post-treatment processes are needed. One of such possibilities is high energy beam treatment of thermally sprayed coatings. During the heat treatment of magnesium substrates with coating the remelting of coating and a thin surface layer of substrate occurs. Depending on the combination of applied coating system and treatment method, different processes can be realised in modified layers: the alloying of magnesium substrate with other elements to improve corrosion properties, redistribution of hard particles from composite coating and new phases formation during the processing to improve the wear resistance of magnesium alloys. In the present work some examples concerning the laser and electron beam treatment of aluminium based composite coatings as well as infra red irradiation of zinc based coatings are described. Coatings are deposited on magnesium substrates (AM20, AZ31, AZ91) by arc spraying with Zn, ZnAl4 and ZnAl15 solid wires and cored wires in aluminium core with powder filling containing different hard particles, such as boron, silicon and tungsten carbide or titanium oxide. Remelting of thermal spray coatings is carried out by means of continuous irradiation of СО 2-laser in nitrogen or argon atmosphere, electron beam in vacuum and focused tungsten halogen lamp line heater in atmosphere. Microstructure of sprayed coatings as well as that of modified surface layers is investigated by metallographic methods. Corrosion properties are estimated by electrochemical measurements. Abrasion wear resistance of the modified layers is determined by scratch test, corundum grinding disk test and Rubber wheel test. It is shown that all methods applied for processing of thermal spray coatings lead to formation of modified surface layers in magnesium substrate with improved wear and corrosion properties. Different mechanisms of microstructure formation such as redistribution of chemical composition of composite coating components, partial remelting of hard phase particles, and new phases formation are discussed. Electrochemical behaviour of modified surface layers is mostly improved due to alloying, homogenization of element distribution and strong decrease of as-sprayed coating porosity. Abrasion wear resistance of processed magnesium substrates strongly depends on the microstructure and usually is 5 to 20 times higher compared with base material.

213 W被覆鋳鉄材の硬さ値分布に及ぼす基材表面粗さと熱処理の影響(コーティング・溶射・薄膜1)

213 W被覆鋳鉄材の硬さ値分布に及ぼす基材表面粗さと熱処理の影響(コーティング・溶射・薄膜1)

Substrate dependent surface plasmon resonance evolution of Ag nanoparticles treated inatmospheres

The evolution of surface plasmon resonance (SPR) with alternate air andH2 treatment was investigated for silver nanoparticles on differentSiO2-based substrates (soda-lime glass, quartz glass and mesoporousSiO2). It has been shown that evolution behaviours on the three substratesare very different. For silver nanoparticles on the mesoporousSiO2 substrate,alternate air and H2 heat treatment led to the alternate disappearance and appearance of the SPR, showing thereversibility of optical changes. For a soda-lime glass substrate, the SPR absorption alsodisappeared after the first run heat treatment in air and re-appeared after subsequentH2 heat treatment, but the second run heat treatment in air could not induce there-disappearance of the SPR. After alternate heating of the sample in air andH2 for four or more cycles, the SPR stayed almost unchanged. For a quartz glasssubstrate, however, the SPR absorption became negligible after alternate air andH2 heattreatment. Such effects of the substrate on the SPR are explained in terms of the subtle difference of thethree SiO2-based substrates in micro-structure or chemical composition, and theredox of silver in the treatment atmospheres. This study could beimportant for the design and architectonics of new optical devices based onSiO2 materials and could also promote the understanding of the interaction of silvernanoparticles with the environment.

The Heat Treatment Characteristics of Hydroxyapatite Thin Films Deposited by RF Sputtering

【RF sputtering process was applied to produce thin hydroxyapatite(HAp) films on Ti-6Al-4V alloy substrates. The effects of different heat treatment conditions on the hardness between HAp thin films and Ti-6Al-4V alloy substrates were studied. Before deposition, the Ti-6Al-4V alloy substrates were heat treated for 1h at $850^{\circ}C\;under\;3.0{\times}10^{-3}torr$ , and after deposition, the HAp thin films were heat treated for 1h at $400^{\circ}C,\;600^{\circ}C\;and\;800^{\circ}C$ under the atmosphere, and analyzed FESEM-EDX, FTIR, XRD, nano-indentor, micro-vickers hardness, respectively. Experimental results represented that the surface defects of thin films decreased by relaxation of internal stress and control of substrate structure followed by heat treatment of substrates before the deposition, and the HAp thin films on the heat-treated substrates had higher hardness than none heattreated substrates before the deposition, and the hardness properties of HAp thin films and Ti-6Al-4V alloy substrates appeared independent behavior, and the hardness of HAp thin films decreased by formation of $VTiO_3(OH),\;{\theta}-Al_{0.32}V_2O_5,\;Al_{0.33}V_2O_5$ .】

652 W被覆鋼材の硬さ値分布に及ぼす基材表面粗さと熱処理の影響(機械材料・新素材I)

652 W被覆鋼材の硬さ値分布に及ぼす基材表面粗さと熱処理の影響(機械材料・新素材I)

Effect of substrate type on nanostructured titania sol–gel coatings for sensors applications

Titania coatings were obtained by the sol–gel method, starting from stable and transparent titania sol. Thin titania coatings were deposited onto different substrates: quartz glass, single crystal quartz (1 0 1), single crystal Si(1 0 0) and alumina. Effect of substrate type and heat treatment conditions on important characteristics determining the sensing properties were studied. Nanostructured titania coatings with grain size up to 50 nm and thickness less than 1 μm were obtained on all substrates, but their phase composition depends on substrate type. The slightly orientation of titania coatings as well as the interactions between titania coating and alumina and silicon single crystal were observed.

Characterization of tungsten oxide films produced by reactive pulsed laser deposition

Tungsten oxide thin films have been prepared by reactive pulsed laser deposition (PLD). Substrate heat treatment and oxygen partial pressure during growth are correlated with Auger electron (AES), X-ray photoelectron (XPS), electron energy loss (EELS) and transmittance spectroscopies. Electronic and mass densities, composition and chemical states are strongly dependent of the deposition conditions. No significant change in the oxygen content in films as a function of substrate or annealing temperature is detected. However, the colored state turns out to be associated to the degree of chemical disorder in the samples, as evidenced by the peak shape of the W 4f transition. Also, the strength of a characteristic energy loss at 6–7 eV appears to be related to the presence of the colored state.

Thermochemical heat treatment of steel substrates using borane–amine adducts as precursors

A novel approach to gas boronising has been carried out to systematically test organoboranes as precursors for low pressure gas boronising. The precursors of the group of borane–amine adducts were synthesised and subsequently applied to gas boronising of steel 42CrMo4 (AISI 4140). Characterisation of the boride layers was performed using glow discharge opticalemission spectroscopy, X-ray photoelectron spectroscopy, SEM, and metallography. Ultramicrohardness was also determined and the wear behaviour was simulated. With the precursors borane–triethylamine adduct and borane–diethylamine adduct gas boronising was possible. Single phased iron boride layers of type Fe2 B with a thickness of several micrometres were generated. The carbon, nitrogen, and oxygen contamination of the boride layers was low. The boride layers are not completely compact which results in a lower hardness compared with commercial powder pack boronised samples. The wear behaviour is similar to powder pack boronised steels and is significantly better than the untreated samples.

Recent progress in plasma nitriding

The paper reports on a new system for plasma nitriding combined with a hollow cathode discharge sputtering at high pressures (about 1000 Pa), a new way of producing duplex coatings, and on a low-pressure (0.1–0.3 Pa) plasma nitriding using microwave discharges. It has been shown that an addition of an auxiliary cathode into a conventional high-pressure nitriding system can improve properties of the nitrided surfaces by incorporation of the elements sputtered from the auxiliary cathode. A converse duplex coating technique consisting of plasma nitriding or vacuum heat treatment of pre-coated substrates has been successfully tested for the protection of aluminium. It has been shown that a low-alloy steel nitriding can be effective not only inside the low-pressure electron cyclotron resonance discharges, i.e. for a standard distance of the substrate from an output of the plasma source, d=250 mm, but also outside these discharges, i.e. for a large distance d=750 mm.

Origins and evolution of stress development in sol-gel derived thin layers and multideposited coatings of lead titanate

Stress development in thin layers of lead titanate prepared by sol-gel processing was monitored by in situ laser reflectance measurements. Layers were spin coated onto silicon substrates and thermally cycled to 500 °C. The shrinkage normal to the rigid substrate was determined by in situ ellipsometry. Changes that occurred on drying and firing, which related to densification and stress development, are reported. The observed changes were explained in terms of evaporation and solvent/polymeric network interactions at lower temperatures, and thermal expansion mismatch between the substrate and the coating after formation of the dense oxide. Crystallization into the perovskite structure occurred only in thicker or multideposited coatings, altering the state of stress from tensile, to progressively more compressive, on cooling. The importance of the choice of substrate material, deposition method and heat treatment conditions, in relation to stress development and dependent electrical properties, are discussed.

Effects of Substrate Temperature and Heat Treatment on GMR Properties of Co–RE–O Nano-granular Films

Effects of substrate temperature and annealing on the giant magnetoresistance (GMR) of Co–RE–O (RE=Y, Nd, Sm, Gd, Tb, Dy) nano-granular films prepared by RF sputtering have been studied. The films consist of the metallic granules with the diameter of about 2–4 nm and oxide insulating narrow intergranules with the width of about 0.5–1 nm. The intergranule is generally connected as a network. The GMR and field response of a film prepared on a heated substrate are larger than those of a film prepared on a water-cooled substrate. The increases in GMR and its field response can be explained by the change in the magnetization curve of films with the growth of Co grains and the structure relaxation. The film structure is almost unchanged by annealing. The GMR and field response of the film are not improved by an annealing.

Effect of substrate temperature and heat treatment on the microstructure of diamondlike carbon films

Nonhydrogenated diamondlike carbon films prepared at a substrate temperature (ST) of 100, 300, and 500 °C by the laser ablation of graphite on a single-crystal silicon substrate have been characterized by scanning tunneling microscopy for the surface structure and Raman spectroscopy for the microstructure. Distorted pentagonal and hexagonal rings are observed on the surface of the film grown at 100 °C while only hexagonal rings are observable for the one grown at 500 °C. The rise in ST is found to increase the surface roughness. To assign the various coexisting carbonaceous species formed at different growth temperatures and to check their thermal stability, heat treatment was performed at up to 1300 °C in vacuum and 600 °C in air. The changes occurring on heat treatment in vacuum in these films around 600 °C have been correlated with the release of defects from the threefold network. Likewise, 950 °C temperature has been associated with the conversion of disordered tetrahedral bonding to a distorted trigonal one. The heat treatment in air shows that the microstructure induced due to lower ST is thermally more stable.

الفائقة الموصليةBSCCO تأثير نوعية المفترش (الطبقة التحتية) والمعاملة الحرارية على خصائص شرائح

The effects of substrate material and heat treatment conditions on the electrical and thermal properties for partially melt-solidified superconducting tapes BSCOO (2212), grown on single crystal MgO and Ag MgO substrates m were investigated. Results show that the resistivity of the normal state varies with the size and orientation of the grains. It is found that larger grains lower both the concentration of second phases and the grain boundaries, hence decreasing the resistivity of the normal state and enhancing the critical current density of the superconducting state. Also, the material of the substrate has no effect on either the resistivity or the critical current density of the Bi-2212 phase. Heat treatment conditions and the annealing atmosphere play an important role in determining the critical current density and the transition temperature. Slow cooling from 840°C lowers both the critical current and the transition temperature; while quenching the sample from 840°C to room temperature and annealing it in a nitrogen atmosphere increase both the critical current density and the transition temperature.

Chemically Vapour Deposited Alumina Coatings on High Speed Steel Cutting Tools

A detailed study has been made of the atmospheric pressure chemical vapour deposition (CVD) of aluminium oxide (Al2O3) coatings on powder metallurgy (PM) BT42 grade high speed steel (HSS) indexable cutting tool inserts. To facilitate this, a laboratory-scale CVD reactor was initially designed and purpose-built. The literature on the effect of process parameters on Al203 coatings chemically vapour deposited on cemented carbide substrates was comprehensively surveyed. With reference to deposition conditions quoted in this literature, a series of trial Al203 coating runs were then performed using uncoated and TiN, TiC and Ti(C1N) precoated PM HSS inserts. Concurrently, modifications to the laboratory-scale CVD reactor were made. Eventually, deposition conditions were established under which a preliminary a Al203 coating could be deposited on the PM HSS inserts and, in the case of the Ti(C1N) precoated inserts only, substantially retained during the obligatory post-coating HSS substrate heat treatment. The effect of the absence/presence and type of precoating on the CVD of AI203 coatings on the PM HSS inserts are discussed. Subsequent coating runs were carried out only on Ti(C1N) precoated inserts. The characteristics of the preliminary AlP, coating on the Ti(C1N) precoated PM HSS inserts were determined, both before and after the obligatory HSS substrate heat treatment, using an established characterisation procedure. This involved the following techniques: X-ray diffraction, Auger electron spectroscopy, optical microscopy, fractography, scanning electron microscopy, microhardness testing, profilometry and scratch-adhesion testing. Although many of the characteristics of the preliminary AI20, coating were found to be inferior to those presented in the literature, they were also established to be essentially unaffected by the post-coating HSS substrate heat treatment. To im prove upon the preliminary Al203 coating, the effect of two of the most important CVD process parameters quoted in the literature; C02JH 2 mole ratio and Alel3 concentration, on the characteristics of Al20, coatings chemically vapour deposited on the Ti(C1N) precoated PM HSS inserts was investigated. Both parameters were found to have a significant effect on Al203 coating characteristics. The reasons for this are discussed in detail.