Deposition of ZnO-Al (AZO) thin films for optical properties

Zinc Oxide (ZnO) is an inorganic compound and it is doped with aluminum to increase its capabilities. Aluminum Zinc Oxide (AZO) thin films are semiconductor materials that have band gap energy of 3.3eV. Various method of deposition have been study to growth AZO thin films. It has been extensively use in solar cell application, display application, gas sensing purposes, and thin film transistors (TFTs). In this work, sol gel method and spin coating was used to deposited AZO thin films. The ZnO sol-gel were synthesized using zinc acetate dihydrate as precursor, isopropanol as solvent, diethanolamine as sol stabilizer, and distilled water as oxidation agent. Then, synthesized ZnO were doped with different mole ratio of aluminum nitrate nanohydrate to produced AZO. The glass substrate was used as substrate and AZO thin films were then calcinated at 300°C and 500°C. The characterization of AZO thin film were done using X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Ultraviolet-visible spectroscopy (UV-Vis), Field Emission Scanning Electron Microscope (FESEM), and Energy Dispersive X-ray spectroscopy (EDX). The XRD results show that the ZnO with hexagonal wurtzite-type structure and temperature does have effect on the film intensity which related to crystallinity of thin films. Through AFM analysis, the value of RMS decreases from 3.018 nm to 2.240 nm as the temperature increases. Meanwhile, from UV-Vis result, it can be seen that AZO thin film have a high transmittance percentage above 90% after wavelength 400 nm with band gap value of 3.3 eV. FESEM image show that the grain boundary of AZO decrease with both parameter (mole ratio and calcinations temperature). Both parameters do have effect on AZO thin film. EDX analysis shows that there are existence of zinc, oxide, and aluminum

Influence of Deposition Parameter to Wear Behaviour of Tungsten Carbide-Nickel (WC-Ni) High Velocity Oxyfuel (HVOF) Coating

This study is done to investigate the influence of deposition parameter to the hardness and wear resistance of the tungsten carbide nickel (WC-Ni) High velocity oxy-fuel (HVOF) coating which is sprayed on the AISI 1040 medium carbon steel. Three different spraying parameters were used with the oxygen flowrate of each being changed and all other parameters and its value is kept constant. Oxygen flowrate of 30, 45 and 60 LPM were used. The result of hardness, wear rate and surface morphology were compared between the coatings. To compare the surface morphology of the three different parameter HVOF coatings, a scanning electron microscope was used. No significant changes shown on the surface of the coatings where all shows the same lump and crevices structure. X-ray diffraction was used to observe the elemental composition on the three coatings, all the coatings have the same elements present on them. It can be seen that all the coatings contains nickel, tungsten carbide, tungsten (II) carbide and oxygen. The method used for hardness test was the Vickers microhardness tester while weight loss test was used to study the wear resistance. Following the test, it is found that the hardness and wear resistance increased as the oxygen flowrate was increased. The highest hardness and wear resistance can be found in the coating with 60 LPM oxygen flowrate

Abrasive wear behaviour of conventional and large-particle tungsten carbide-based cermet coatings as a function of abrasive size and type

Abrasive wear behaviour of materials can be assessed using a wide variety of testing methods, and the relative performance of materials will tend to depend upon the testing procedure employed. In this work, two cermet type coatings have been examined, namely (i) a conventional tungsten carbide-cobalt thermally sprayed coating with a carbide size of between ∼0.3 – 5 μm and (ii) a tungsten carbide-nickel alloy weld overlay with large spherical carbides of the order of ∼50 – 140 μm in diameter (DuraStell). The wear behaviour of these two materials has been examined by the use of two abrasion tests, namely the micro-scale abrasion test using both silica and alumina abrasives (typically 2-10 μm in size), and the dry sand-rubber wheel test (ASTM G65), again with both silica and alumina abrasives (typically 180 – 300 μm in size). It was found that when the abrasive particles were of the same scale or larger than the mean free path between the hard phase particles, then the matrix phase was well protected by the hard phases. Testing (in both test types) with alumina abrasives resulted in wear of both the hard carbide phases and the matrix phases in both the thermally sprayed coating and the weld overlay, with the thermally sprayed coating exhibiting lower wear rates. The wear behaviour of the materials with the more industrially relevant silica abrasive was more complex; the thermally sprayed coating exhibited a lower wear rate than the weld overlay with the fine abrasive in the micro-scale abrasion test due to effective shielding of the matrix from abrasive action due to the fine reinforcement particle size. In contrast, with the coarser silica abrasive in the dry sand-rubber wheel test, the weld overlay with the large carbides was able to provide matrix protection with low rates of wear, whereas the thermally sprayed coating wore by fracture of the more brittle microstructure. These findings demonstrate the importance of selection of appropriate laboratory test procedures and abrasives to simulate behaviour of materials in service environments

Influence of deposition parameter to wear behaviour of tungsten carbide-nickel (WC-Ni) high velocity oxyfuel (HVOF) coating

This study is done to investigate the influence of deposition parameter to the hardness and wear resistance of the tungsten carbide nickel (WC-Ni) High velocity oxy-fuel (HVOF) coating which is sprayed on the AISI 1040 medium carbon steel. Three different spraying parameters were used with the oxygen flowrate of each being changed and all other parameters and its value is kept constant. Oxygen flowrate of 30, 45 and 60 LPM were used. The result of hardness, wear rate and surface morphology were compared between the coatings. To compare the surface morphology of the three different parameter HVOF coatings, a scanning electron microscope was used. No significant changes shown on the surface of the coatings where all shows the same lump and crevices structure. X-ray diffraction was used to observe the elemental composition on the three coatings, all the coatings have the same elements present on them. It can be seen that all the coatings contains nickel, tungsten carbide, tungsten (II) carbide and oxygen. The method used for hardness test was the Vickers microhardness tester while weight loss test was used to study the wear resistance. Following the test, it is found that the hardness and wear resistance increased as the oxygen flowrate was increased. The highest hardness and wear resistance can be found in the coating with 60 LPM oxygen flowrate

Microstructure analysis of tungsten carbide hardfacing on carbon steel blade

Tungsten carbide (WC) hardfacing coating is commonly used to enhance carbon steel blade performance which works in acidic and abrasive condition during production process. This paper deals with tungsten carbide (WC) hardfacing microstructure analysis on a carbon steel blade. Mixing of ilmenite ore with sulphuric acid is performed by the carbon steel blade as part of a production process. Tungsten carbide hardfacing is deposited on the carbon steel blade to enhance its wear resistance. The carbide distribution along with elemental composition analysis of the hardfaced carbon steel blade specimens is examined using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) respectively. Microstructure analysis revealed that different sizes of carbides with non-uniform distribution are found around the coating region. The carbide region is contains high percentage of tungsten (W) meanwhile, non-carbide region rich in tungsten (W) and iron (Fe)

Development of visible light-responsive mono and codoped TiO2 for photocatalytic degradation of methyl orange dye

Titanium dioxide (TiO2) has been acknowledged as a promising photocatalyst in environmental remediation including wastewater treatment. In this study, TiO2 nanoparticles either by single or co-doped of iron (Fe) and nitrogen (N) via sol-gel method and calcined at 500 °C for 3 hours. This experiment investigated the performance of mono/co-dopant of TiO2 photocatalyst against methyl orange in aqueous solution under UV light irradiation. The experimental results showed the rate of degradation favored in co-doped TiO2 followed by mono doped TiO2 and pristine TiO2. The photocatalytic reaction followed pseudo first-order kinetics which were rationalized in terms of the Langmuir– Hinshelwood model and provided nearly complete degradatio

Wear behavior of heat-treated coated carbon steel

A particular type of steel has a higher concentration of carbon than other types of steel called carbon steel. This study focused on the electrodeposition coating of Nickel Silicon Carbide (Ni-SiC) composite coating at 50 oC. In this study, medium carbon steel was used as a substrate. 25 g/l SiC was used during the deposition. The carbon steel was acted as the cathode and the carbon rod as an anode during electrodeposition. The coated sample was heat-treated at 350 OC for 1 hour. Scanning Electron Microscope (SEM) was used to analyze the surface morphology and microstructure of the coated and heat-treated sample before and after the wear test. The coated sample's element composition and phase distribution are determined using the Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD). To identify the hardness of the composite coating, Vickers micro-hardness test was used on the surface of the sample with 100g load in 10 seconds with ten indentations. Weight loss method was conducted to determine the average wear resistance of the sample. The wear behavior of the Ni-SiC was evaluated using the weight loss method with 3 g/l alumina as the abrasive material. The results showed that the heat-treated coating had higher wear resistance than the without heat treatment. The findings also showed that the sample with the heat-treatment process had a higher hardness. This proved that the heat-treated sample had the best wear behavior and hardness value compared to without heat treatment due to denser coating produce

Abrasive wear behaviour of conventional and large-particle tungsten carbide-based cermet coatings as a function of abrasive size and type

Abrasive wear behaviour of materials can be assessed using a wide variety of testing methods, and the relative performance of materials will tend to depend upon the testing procedure employed. In this work, two cermet type coatings have been examined, namely (i) a conventional tungsten carbide-cobalt thermally sprayed coating with a carbide size of between ∼0.3 – 5 μm and (ii) a tungsten carbide-nickel alloy weld overlay with large spherical carbides of the order of ∼50 – 140 μm in diameter (DuraStell). The wear behaviour of these two materials has been examined by the use of two abrasion tests, namely the micro-scale abrasion test using both silica and alumina abrasives (typically 2-10 μm in size), and the dry sand-rubber wheel test (ASTM G65), again with both silica and alumina abrasives (typically 180 – 300 μm in size). It was found that when the abrasive particles were of the same scale or larger than the mean free path between the hard phase particles, then the matrix phase was well protected by the hard phases. Testing (in both test types) with alumina abrasives resulted in wear of both the hard carbide phases and the matrix phases in both the thermally sprayed coating and the weld overlay, with the thermally sprayed coating exhibiting lower wear rates. The wear behaviour of the materials with the more industrially relevant silica abrasive was more complex; the thermally sprayed coating exhibited a lower wear rate than the weld overlay with the fine abrasive in the micro-scale abrasion test due to effective shielding of the matrix from abrasive action due to the fine reinforcement particle size. In contrast, with the coarser silica abrasive in the dry sand-rubber wheel test, the weld overlay with the large carbides was able to provide matrix protection with low rates of wear, whereas the thermally sprayed coating wore by fracture of the more brittle microstructure. These findings demonstrate the importance of selection of appropriate laboratory test procedures and abrasives to simulate behaviour of materials in service environments

Wear behavior of heat-treated coated carbon steel

A particular type of steel has a higher concentration of carbon than other types of steel called carbon steel. This study focused on the electrodeposition coating of Nickel Silicon Carbide (Ni-SiC) composite coating at 50 oC. In this study, medium carbon steel was used as a substrate. 25 g/l SiC was used during the deposition. The carbon steel was acted as the cathode and the carbon rod as an anode during electrodeposition. The coated sample was heat-treated at 350 OC for 1 hour. Scanning Electron Microscope (SEM) was used to analyze the surface morphology and microstructure of the coated and heat-treated sample before and after the wear test. The coated sample's element composition and phase distribution are determined using the Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD). To identify the hardness of the composite coating, Vickers micro-hardness test was used on the surface of the sample with 100g load in 10 seconds with ten indentations. Weight loss method was conducted to determine the average wear resistance of the sample. The wear behavior of the Ni-SiC was evaluated using the weight loss method with 3 g/l alumina as the abrasive material. The results showed that the heat-treated coating had higher wear resistance than the without heat treatment. The findings also showed that the sample with the heat-treatment process had a higher hardness. This proved that the heat-treated sample had the best wear behavior and hardness value compared to without heat treatment due to denser coating produce

Abrasive wear failure analysis of tungsten carbide hard facing on carbon steel blade

This study investigate the abrasive wear failure of tungsten carbide hardfacing on continuous digester (CD) blade (carbon steel) in an environment of sulphuric acid and ilmenite ore mixture. Comparison being made on the hardness, thickness and microstructural of the hardfacing between unworn and 3 months old worn blade on few locations around the blade. The cross sections of the blade revealed non-uniform coverage of the hardfacing on the blade for both worn and unworn blade. The edge of the blade has the least amount of hardfacing thickness which with time acts as the point of failure during the wear process. The hardness obtained from both the unworn and worn samples are around 25% lower from the hardfacing electrode manufacturer’s hardness specification. Microstructural micrograph analysis of the hardfacing revealed non uniform size carbide with non-uniform distributed of carbide in the hardfacing layer