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In the present work, 16% chromium AISI 430 ferritic stainless steel weld produced under different conditions of energy input and metal powder addition using TIG torch melting is investigated for carbide precipitation. A Box Behnken experimental design paradigm is invoked with current, speed and metal powder concentration as the primary variables while type of powder is the categorical variable. The result indicates that for a given concentration of metal powder in the melt pool, the sensitized geometry increases with energy input. Titanium as well as the mixture of aluminum and titanium powders reduces the width of the sensitized zone while aluminum powder increases the width of the zone. Titanium powder prevents the development of completely ditched structure in the high temperature heat affected zone (HTHAZ) whereas aluminum powder accelerates the formation of ditched structure in the HAZ.

Eutectoid steel with full pearlitic microstructure is hard and strong. Near eutectoid steels containing pearlite and proeutectoid ferrite or cementite micro-constituents do not give that unique properties. Isothermal transformation treatments with precise control of cooling temperature produce fully pearlitic microstructure of fine lamellar spacing in near eutectoid steels. The cold drawn wire of this fine pearlite steel is one of the strongest materials used in music wire where the strings are tuned under tension. Carbon–manganese steels containing 0.65–0.84%C and 0.70–1.10%Mn transform to pearlite upon air-cooling, which develops wear resistance and hardness properties suitable for rails application. These properties further increase with finer interlamellar spacing generated by reducing transformation temperature.

Cobalt-based alloys are used as wear resistant, magnetic, and high strength materials. Alloying with nickel, chromium, Ta, W, Nb and Mo develop some extremely important properties such as fatigue and creep strength at high temperatures, and resistance to sulfidation. 20–30% Cr additions provide oxidation and hot corrosion resistance. In cobalt alloys hardening occurs by precipitation of carbide during heat treatment. A new class of ?–?' cobalt-based superalloy has been reported and the optimum composition of the quaternary alloy is Co–10Al–5Mo–2 Nb. It has superior mechanical properties at high temperatures than the existing polycrystalline Co-based and Ni-based superalloys. Most of the commercial cobalt alloys are known with trademarks. The Stellite trademark, which was applied to the first cobalt wear alloys, is still in use. The Unified Numbering System has been used to designate a number of commercial cobalt alloys.

We study the change in the structural morphology and optical properties of aqueous solution grown ZnO microrods on glass substrates with the change in the concentration of hexamethylene tetramine (HMT). The field emission scanning electron microscope images of the microrods grown for equimolar (1:1) ratio of Zn2+ salt and HMT exhibit the highest aspect ratio, 8.3, which decreases gradually, while the relative intensity of the (100) peak in the X-ray diffractogram increases with increase in the HMT concentration. The change in the morphology from a perfect hexagonal to an oval-shaped needle is experimentally supported by the high-resolution transmission electron microscope results. A sharp and strong ultraviolet photoluminescence peak ensures good structural quality of the microrods for the molar ratios 1:1 and 1:3 above which the quality degrades. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Mg x Zn1−x O (x = 0.0–0.08) thin films have been deposited on glass substrate by sol–gel technique and photoconductivity of the thin films have been investigated in vacuum, hydrogen, oxygen and air. Photoresponse spectra show that both ZnO and substituted films are ultraviolet light sensitive and the sensitivity shifts towards the shorter wavelength side with increasing x. The photo-to-dark current ratio (I ph/I d) and decay times are influenced by different ambient such as vacuum, hydrogen, and air for all the substituted films. I ph/I d for the substituted films increases first attaining a maximum value for x = 0.05 and then decreases for vacuum and hydrogen, while, an increase in the value is observed incase of oxygen as x increases. The change is not significant in air. The value of photo to dark current ratio for the films with x = 0.05 and 0.08 is as high as four orders of magnitude in both vacuum and hydrogen ambient. This change in the photo to dark current ratio is correlated with the grain boundaries, hence, the grain size of the films. In vacuum, hydrogen and oxygen, though a large increase in the photocurrent is caused, both growth and decay process becomes slower in these ambient.

A series of n-ZnO/p-Si thin film heterojunctions have been fabricated by a low cost sol–gel technique for different ZnO film thicknesses and the dark as well as photo current–voltage (I–V) characteristics have been investigated in details. The heterojunction with ZnO thickness of 0.46 μm shows the best diode characteristics in terms of rectification ratio, IF/IR = 5.7 × 103 at 5 V and reverse leakage current density, JR = 7.6 × 10−5 A cm−2 at −5 V. From the photo I–V curves and wavelength dependent photocurrent of the heterojunctions, it is found that the junction with 0.46 μm ZnO thickness shows the highest sensitivity towards both UV and visible lights.

ZnO thin films are deposited on the glass substrates by sol–gel drain coating technique by varying the concentration of the sol. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of sol concentration on the crystallinity and surface morphology of the films. The results show that with increase in sol concentration, the value of full width at half maximum (FWHM) of (0 0 2) peak decreases while the strain first increases and then decreases. The sol with higher concentration results in the increase in the grain size. The studies on the optical properties show that the band gap value increases from 3.27 to 3.3 eV when the sol concentration changes from 0.03 to 0.1 M. The photoconductivity studies reveal that the film for 0.05 M sol shows the maximum photoresponse for ultraviolet (UV) wavelength (

Gold is the most precious metal and widely used for monetary commodity. Pure gold is very soft, malleable, and highly resistant to corrosion. Alloying with silver, copper, nickel, platinum, zinc, and thermal processing make gold stronger. Gold alloying generates several attractive colors for jewelry applications. Purity of gold is designated by karat, and 24 karat (24 K) gold is 1000 fine or pure gold. Gold has other uses in dentistry, semiconductor industries, scientific equipment, and sensing metal ions in environmental and bio applications.

Aluminum is very attractive in many engineering applications for its low density. By alloy addition, cold working and/or heat treatment can develop a high specific strength. Numerous aluminum alloys are available as cast, wrought and/or heat-treated products for various applications. These materials are classified using a standard designation system; the wrought having a 4-digit system, and the castings having a 3-digit and 1-decimal place system. The first digit identifies the alloy group and the second two digits identify composition. Letters added as suffixes to the alloy number indicate various tempers developed by different treatments. One or more digits following the letter indicate subdivisions of the tempers, when they significantly influence the characteristics of the alloy.

Nickel is a versatile element and it alloys with most metals. Nickel alloys have wide variety of applications including low-expansion alloys, electrical resistance alloys, soft magnetic alloys, and shape memory alloys. However, majority of these alloys are employed in places where they are subjected to harsh environments at high temperatures. The nickel–chromium alloys particularly are popular for applications in power plants and turbine engines because of its excellent strength and resistance to corrosion and oxidation at high temperatures. Commercial nickel alloys developed by different producers for specific applications are marketed using individual trademarks with various identification systems. A generic coding number for these alloys have been designated with the Unified Numbering System, although it does not define any requirements for form, condition, or properties.

Silver is the most plentiful of the precious metals. It is a very soft metal and has high resistance to corrosion and oxidation properties. The hardness and strength of this material are enhanced by alloy additions and heat treatments. Silver has wide applications in jewelry, decorative art, coins, and tableware. Because of high electrical conductivity, high temperature mechanical and functional properties, silver alloys have extensive use in electronic industries, brazing, heavy-duty bearings, and electrical contracts. Alloys of silver-metal oxides are mainly used in low voltage electrical switching devices like relays, installation and distribution switches, appliances, industrial controls, motor controls, and protective devices properties. Silver alloys are developed as substitute of high cost gold alloys for dental applications.

A series of Al doped ZnO (ZnO : Al) films with different Al concentrations have been deposited on glass substrates using the sol–gel spin coating technique and the effect of Al concentrations on the structural, electrical, optical and photoresponse properties have been investigated. The XRD results show the presence of peaks due to the reflections of the planes from a wurtzite type of ZnO structure. The surface morphology shows that the grains become non-uniform and smaller in size as the Al doping level increases. For 1–2% Al doping, the film attains highest carrier concentration of about ~2.7 × 1019 cm−3 and lowest resistivity of ~2 × 10−2 Ω cm. The excitonic nature in the absorption spectrum disappears for doping above 1%. The band gap increases with the increase in the Al concentration. The photoconductivity studies show that although the photoresponse properties are degraded due to incorporation of Al atoms, the 1% Al doped film shows the best photoresponse properties within the doping limit up to 5%.

In the present study, oil palm wood flour (OPWF) particles with less than 250 μm sizes have been used as filler materials in the woven-glass-fiber reinforced epoxy composite. The hybrid composites were fabricated using a hand lay-up method and cured at room temperature under a compressive load of 196 N (20 kg). The OPWF of 2.5 to 10 parts per hundred (pph) by weight was used to evaluate its effect on impact strength of the hybrid composites at a range of temperature from −50 to 50 °C. The impact strength, evaluated using V-notch Charpy method, showed reduction with increasing filler content up to 5 pph and then the strength increment in those composites containing more than 5 pph OPWF. More severe damages were found in specimens with higher filler contents resulting higher energy absorption during impact. The composites with a large amount of OPWF particles deflected crack propagation paths or created obstacles at the crack tips and increased toughness of the composites. The impact strength was found to decrease when the samples fractured at subzero temperatures and this happened because of the reduction of the matrix ductility at lower temperatures.

We report on the ultraviolet (UV) photodetection properties of a Pt contact on a sol-gel Mg0.1Zn0.9O/ZnO composite structure on a glass substrate. In the dark, the current–voltage (I–V) characteristics between the Pt and Ag contacts on the top of the ZnO film were linear while that on the Mg0.1Zn0.9O/ZnO composite film were rectifying, suggesting the formation of a Schottky diode on the latter. The ideality factor, n, and the reverse leakage current density, J R , of the Schottky diode were greater than 2 and 2.36 × 10−2 A cm−2 at −5 V, respectively. Under ultraviolet light, the I–V characteristics become linear. The maximum photo-to-dark current ratio observed was about 63. The composite film showed good sensitivity to UV light with wavelengths of less than 400 nm, though the photoresponse process was found to be slow.

A series of ZnO films of different thickness have been deposited on glass substrates using sol-gel technique by varying the number of spin coatings and the effect of film thickness on the structural, electrical and optical properties have been investigated. The XRD results indicate that the full width at half maximum (FWHM) of the (0 0 2) diffraction peak and the strain along c-axis are decreased as the film is grown up to a thickness of 300 nm. Above 300 nm, the strain again becomes appreciable. The surface morphology shows that the grains become more uniform and bigger in size as the film thickness increases. Electrical result shows that although ZnO film with thickness of around 260 nm has the highest resistivity but is better for current conduction. The excitonic nature in the absorption spectrum becomes prominent for a film with thickness of around 260 nm. The band gap increases and then decreases as the film grows thicker.

We report on the bias-dependent photodetection of two different wavelengths of photons in the ultraviolet (UV) region by Au-Mg0.1Zn0.9O/ZnO-Ag structure deposited on a glass substrate by the sol-gel technique. Without the cap layer of Mg0.1Zn0.9O, the current-voltage (I-V) characteristic is symmetric and linear for positive and negative bias conditions. The presence of a cap layer on top of ZnO resulted in an asymmetric I-V curve and also decreased the dark current for both bias voltages applied to the Au contact. The structure shows maximum photoresponse at 370 nm and 320 nm when the Au contact is positively and negatively biased, respectively. The photo-to-dark current density ratio is about 48 at +20 V.

The dependence of photoconducting properties on the thickness of ZnO films deposited on glass substrates by sol–gel spin coating technique has been investigated. The X-ray diffraction (XRD) results indicate that the film with thickness of 260 nm becomes maximum oriented along (0 0 2) direction. The field emission scanning electron micrograph (FESEM) shows that the grain size and volume of micropore increases with increase in thickness. Calculation shows that 260 nm film has the highest porosity. The photoconductivity studies exhibit maximum photoresponse for ultraviolet (UV) wavelength (

A p-CuO/n-ZnO thin film heterojunction is fabricated on a glass substrate by the sol–gel technique. The crystallinity of the junction materials and microstructure of the top p-layer are examined by an x-ray diffractometer (XRD) and scanning electron microscope (SEM). The current–voltage (I–V) characteristics of the p–n heterojunction and its temperature dependence have been investigated in air and H2 ambient. Although the junction possesses linear I–V characteristics from room temperature (RT) to 150 °C in air, at higher temperatures (200 °C to 300 °C), it shows nonlinear rectifying behaviour. The forward current is greatly increased with increasing temperature while the reverse current is increased slightly resulting in a IF/IR ratio as high as 485. The ideality factor (n) is 4.88 at a temperature of 300 °C. The forward current is highly increased by the introduction of H2 gas at 300 °C. However, a simultaneous increase in the reverse current makes the IF/IR ratio 8.4. It is observed that H2 sensitivity of the heterojunction is increased with the increase in temperature as well as the thickness of CuO film. A sensitivity value as high as 266.5 is observed at 300 °C when biased at 3 V in the presence of approximately 3000 ppm of H2.

The ability of the atomic force microscope (AFM) technique to detect and to characterize surface roughness of as-deposited and thermally annealed borophosphosilicate glass (BPSG) films, deposited using atmospheric and sub-atmospheric pressure TEOS-ozone based chemical vapor deposition (CVD) as well as atmospheric and low pressure silane-based CVD, have been demonstrated. The as-deposited BPSG films processed under atmospheric pressure conditions produced higher surface roughness than BPSG films deposited at a reduced pressure. Thermal treatment of BPSG glass films smoothened the film surface roughness. However, the liquid defects on the film surface were found to affect the accuracy of the roughness measurements. The AFM demonstrated to be a quick and non-destructive technique for the characterization of BPSG planarization in terms of flow angle on the step model of integrated semiconductor circuit devices. The correlation between AFM flow angle and scanning electron microscopic analysis of the same device areas showed a linear dependency for angles less than 80°.

The properties of electroplated copper film have been investigated as a function of annealing temperatures together with the diffusion barrier performance. Electroplated copper films on copper and tungsten seed materials were annealed from 300 to 700 °C in N2 atmosphere for grain growth study. The average grain size of the as-deposited copper films was found to be different; larger copper grains (0.6 μm) were formed on the W seed layer compared to those formed on Cu (0.2 μm). The copper films also started to recrystallize at 300 °C and grain growth occurred from 400 °C onward. Regardless of the initial grain size of the electroplated copper films, the final grain size was found to be similar on both seed materials. After 600 and 700 °C annealing, the average grain sizes became 1.00 and 1.20 μm, respectively. The driving force for grain growth is from the elimination of grain boundaries where the surface energy is being released to achieve the equilibrium state. The annealed films produced a layered micros...

An activated-carbon (AC) assisted route is developed to synthesize a ZnO nanoparticle network. The route involves simple addition of AC to the solution containing the zinc salt and finally removing them by burning at higher temperature to form a sponge-like porous ZnO nanoparticles. The surface area measurements show that AC-assisted ZnO nanoparticles (AC-ZnO) have a higher surface area than those synthesized without AC (B-ZnO), which is further confirmed by the field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM) images. Ultraviolet (UV) absorbance results show that the optical quality remains almost unchanged for both types of nanoparticles. Enhanced and faster UV photosensitivity has been observed for the AC-ZnO. The change in the UV photosensing properties demonstrated here provides a new approach to synthesizing other high surface area materials for novel physical and chemical properties.

We have fabricated a ZnO nanowire (NW)/La(0.65)Sr(0.35)MnO(3) (LSMO) p-n heterojunction by growing the NWs by an easy aqueous chemical route on a pressed powdered pellet of LSMO. The NWs have hexagonal wurtzite structure with good optical emission properties. The current-voltage (I-V) curves of a single NW junction measured by a scanning tunneling microscope (STM) probe show excellent rectifying behavior with rectification ratio approximately 40, which is comparable to the characteristics of the junction made by large area NW array junctions. Different voltage-dependent current transport mechanisms have been found, which are explained through the use of a band diagram.

A study was carried out to investigate the effect of current density and pulse waveform on the filling of line trenches and contact vias with aspect ratio of 2:1 for sub-0.25 µm device manufacturing using normal pulse plating of copper. The growth pattern of the copper films deposited using 0.05 and 0.10 A/cm2 current density gave no significant difference. Small grains were seen to have nucleated uniformly across the line trenches and via holes after 1 second of electroplating. With increasing the deposition time to 2 seconds, a slight buildup of the film thickness was observed in both trenches and vias without significant increase in the size of the copper grains. Grain growth involving the coalescence of small grains occurred after 5 seconds of plating and a further buildup in thickness and fill up of the trenches and vias occurred after 10 seconds of deposition.When the patterned wafers were plated with a pulse waveform of 3 ms on and 0.5 ms off, the filling of trenches could not be complete after 30 seconds of electroplating. A complete filling of the trenches was achieved within 30 seconds of deposition using a pulse waveform of 6 to 8 ms on and 1 to 2 ms off. When the on-period was increased above this range to 9.9 ms, voids were observed at the centre of the via holes.

Publisher Summary This chapter describes the characteristic differences in microstructure and hardness of the composite layers produced in a helium and nitrogen environments, and is characterized in terms of microstructure, layer thickness, surface cracking, and hardness. In the present study, 5 and 10 vol% of 3 μm size SiCp powders are used. Laser melting in a nitrogen environment dissolved all SiCp, and the metal matrix composite (MMC) track consisted of dendrites at the top surface followed by thread-like particles. The MMC layer produced under a helium environment resulted in a dissolution of SiCp and precipitation of TiC or partial dissolution of SiCp and agglomeration into a band. In the nitrogen environment, the dendrites are very compact after glazing at high-energy densities. The tracks glazed under a helium environment are free from surface cracking, but those produced in a pure nitrogen environment contained cracks. The melted layer thicknesses are seen to be 2 to 4 times greater than for tracks produced in a helium environment. The dendritic structures of nitride/carbonitride developed higher hardness, and the extra thermal energy released from nitride formation in the applied nitrogen environment, increased the melt temperature and the melt depth, as compared to those tracks produced using a helium environment. The microstructure produced in a helium environment is dominated by dissolution of SiCp and formation of thread-like particles. These observations suggest that cracking is related to high hardness, which in turn is associated with agglomeration of hard particles.

The effect of Cu doping (0.08-4%) on the structural, electrical, optical, and optoelectronic properties of sol-gel ZnO thin films deposited on glass substrates have been investigated. X-ray diffraction studies show that the doped films are single-phase wurtzite structure with random orientations. A decreasing trend in the c-axis parameter up to 0.5% is observed followed by an increasing trend above that. Field-emission scanning electron microscopy shows a grain texture. The energy dispersive spectroscopy as well as the film color confirms the Cu doping. Optical transmittance measurements show 80% transparency in the visible region for the films up to 0.3% Cu content. The doped films become very resistive as indicated by the four probe electrical resistivity and current-voltage measurements. The photoluminescence spectra reveal with Cu doping, a green emission at 515 nm appeared and the UV peak intensity at 376 nm is drastically lowered. However, no green emission is observed as the doping is increased beyond 0.5%. The changes in the structural, electrical, and optical properties are correlated to interstitials defects. The photoconductivity studies show that the UV sensitivity of the films is enhanced up to 0.1%, which indicates that the films can be used as UV sensors.

A simple route for the synthesis of a novel mesoporous zinc oxide material having wurtzite like nanocrystalline pore walls by using Schiff-base amine as template is reported, which shows very high BET surface area (456 m(2) g(-1)) and remarkably enhanced photoconductivity and photoluminescence at room temperature under visible light irradiation vis-à-vis bulk ZnO material.

Single layer ZnO/polyaniline (PANI) inorganic/organic hybrid structure fabricated on glass substrate by depositing polyaniline film on the sol-gel ZnO thin film shows a rectifying behavior indicating the formation of a diode. The current transport mechanism is modeled through an energy band diagram. The heterojunction is sensitive to UV illumination. The photo-to-dark current ratio of the junction is about 46 for −5V bias. The photoresponse parameters of the diode are found to be better than those of only ZnO film of similar thickness. The results indicate that the ZnO/PANI hybrid structure might be promising for the UV photodetection applications.

A n‐ZnO∕p‐Si thin film heterojunction has been fabricated by a low cost sol-gel technique. The wavelength dependent photoresponse properties of the heterojunction is investigated in detail by studying the effect of light illumination on current-voltage (I‐V) characteristics, photocurrent, and photocapacitance spectra at room temperature. It shows good diode characteristics with IF∕IR=3.4×103 at 4V and reverse leakage current density of 7.6×10−5Acm−2 at −5V. From the photocurrent spectra, it is observed that the visible photons are absorbed in the depleted p‐Si under reverse bias conditions, while ultraviolet (UV) photons are absorbed in the depleted n‐ZnO under positive bias conditions. This indicates that such a sol-gel n‐ZnO∕p‐Si thin film heterojunction can be used to sense both UV and visible photons though the photoresponse for UV is much slower than that of visible. The photocapacitance measurements suggest the presence of a shallow defect level in the sol-gel derived ZnO film which acts as an elect...

Copper films were electroplated on either W/TiN/Si(100) or Cu/TaN/Si(100) surfaces with copper electrolytes containing different types of acids, namely, H2SO4, HCl, HNO3, and HF. The properties of these copper films were then characterized in terms of their microstructure and electrical properties. Dense copper films were obtained from H2SO4 and HNO3-based electrolytes, which produced films consisting of small equiaxed grains with average grain sizes of 0.25 μm whereas larger grains of 0.5 μm were obtained from a HF-based electrolyte. However, a very rough Cu film with copper chloride residues was obtained from the HCl-based electrolyte. For W seeded substrates, strong 〈111〉 oriented copper films were produced while both 〈111〉 and 〈220〉 were observed as the preferred orientations of the film on Cu seeded substrates. Both H2SO4- and HNO3-based electrolytes were able to produce films with bulk resistivity as low as 1.82 μΩ cm on Cu seeded substrates. For W seed, the bulk resistivity varied between 1.92 and ...

A number of etching reagents have been appraised with a view to establishing a simple technique for distinguishing the different phases in the compound zone of nitrided irons and steels, and distinguishing the different microconstituents in the nitride alloy steels. Oberhoffer's reagent is found to be the best single etchant, and its action and that of the other etchants investigated are described.