Influence of Annealed Aluminum Properties on Adhesion Bonding of Cold Sprayed Titanium Dioxide Coating

It is well known that cold spraying ceramic materials can be difficult because cold spraying requires plastic deformation of the feedstock particles for adhesion to the substrate. The challenge lies in the difficulty of plastically deforming hard and brittle ceramic materials, such as TiO2. Previous studies have reported the possibility of cold spraying thick pure TiO2 but the bonding mechanism of cold sprayed TiO2 is not fully understood. The factor like substrate condition as oxide film thickness and mechanical properties may also affect cold spray deposition but not fully understood in cold spraying ceramic. The aim of the present research is to investigate the correlation between the oxide thickness and substrate deformation with the adhesion strength of cold-sprayed TiO2 coatings toward the bonding mechanism involved. Relevant experiments were executed using Al 1050, subjected to various annealing temperatures and cold-sprayed with TiO2 powder. The results indicate a decreasing trend of coating adhesion strength with increasing annealed substrate temperature from room temperature to 400°C annealed. Metallurgical bonding is pronounced as bonding mechanism involved between TiO2 particle and annealed 1050 substrate

Electrophoretic deposited LSCF-SDCC-Ag cathode coating on ferritic stainless steel interconnect for SOFC

The application of electrophoretic deposition (EPD) technique in development of composite cathode as a coating layer on ferritic stainless steel (FSS) interconnect for solid oxide fuel cell (SOFC) has acquired a great interest. The aim of this study is to determine the capability of EPD technique in producing composite cathode coating. The lanthanum strontium cobalt ferrite (LSCF)-samarium doped ceria carbonate (SDCC) composite cathode powder with silver (Ag) addition was fabricated adopting the EPD technique. LSCF-SDCC-Ag suspension was prepared by using organic-aqueous solvent for the deposition. The coated FSS substrate was first heat treated at 600°C for 90 minutes in air. The deposition was carried out at different applied voltages (5, 7 and 10 volt) and deposition durations (5-20 minutes). The increment of applied voltage and deposition duration was found to contribute to the increment of LSCF-SDCC-Ag deposited weight. The highest deposited weight and thickness of coating was 2.47 mg/cm² and 62.73 µm respectively attained by deposition of 10 volt for 20 minutes. According to the obtained results, deposition at 10 volt within 5 to 20 minutes has shown a better deposition. It is thus clear that EPD is indeed a feasible technique applicable for the development of composite cathode for SOFC interconnects and yielded better coating thicknesses of LSCF-SDCC-Ag on FSS interconnect for SOFC

A preliminary study into the effect of oxide chemistry on the bonding mechanism of cold-sprayed titanium dioxide coatings on SUS316 stainless steel substrate

Current attention has focused on the preparation of thick ceramic coating of nano­structured materials as feedstock material using the thermal spray process. The cold spray method has appeared as a promising process to form ceramic nanostructured coating without significantly changing the microstructure of the initial feedstock materials due to its low processing temperature. However, deposition of ceramic powders by cold spray is not easy due to the brittle characteristics of the material. In this study, TiO2 coatings were deposited on unannealed stainless steel substrates and substrates that were annealed from room temperature to 700 °C prior to spraying. The adhesion strength was evaluated to investigate the bonding mechanism. The influence of the remaining surface oxide layer of chromium oxide, Cr2O3, which is thermodynamically preferred for stainless steel, on the bonding mechanism involved was investigated. The results showed that by increasing the annealing substrate temperature of stainless steel, the adhesion strength of the coatings (thicker oxide) is also increased. As a result, the bonding between the cold-sprayed TiO2 particle and the steel substrate is given by the chemical bonding of an inter-oxide reaction

Deposition of Titanium Dioxide Coating by the Cold-Spray Process on Annealed Stainless Steel Substrate

The surface of most metals is covered with thin native oxide films. It has generally been believed that to achieve bonding, the oxide covering the surface of metallic particles or metal substrates must be broken and removed by adiabatic shear instability (ASI), whether induced at the particle–substrate interface or at the particle–particle interface. The aim of the present research is to investigate the correlation between the remaining oxide amorphous layer and substrate-deformation with the adhesion strength of cold-sprayed TiO2 coatings towards the bonding mechanism involved. Relevant experiments were executed using stainless steel (SUS 304), subjected to various annealing temperatures and cold-sprayed with TiO2 powder. The results indicate an increasing trend of coating adhesion strength with increasing annealed substrate temperature. The influence of substrate plastic deformation and atomic intermixing at the remaining amorphous oxide layer is discussed as the factors contributing to the increasing adhesion strength of cold-sprayed TiO2 coatings

Influence of Substrate Properties on Bonding Mechanism of Cold Sprayed Titanium Dioxide Coating

豊橋技術科学大

SYNTHESIS AND CHARACTERIZATION OF IRON OXIDE NANOLEAF BY THERMAL OXIDATION

In this work, a simple method for the efficient and rapid synthesis of onedimensional hematite (α-Fe2O3) nanostructures is proposed based on a thermal oxidation approach. This technique is to create iron oxide nanoleaf on the iron (Fe) substrate. The oxidation was done at three different temperatures (200-600 oC) by oxidizing the Fe foils in a chamber furnace. The low temperature thermal oxidation at 400 oC for 2 h resulted in the formation of hematite iron oxide with good nanoleaf coverage on the foil surface. The obtained nanostructures physical and structural characteristics were characterize using XRD, and Raman spectroscopy. While their morphological characteristics were observed using the FESEM. It was discovered that when the oxidation period lengthened, the peak intensities in relation to the hematite increased. The duration of heating has a substantial impact on the development and ultimate morphology of hematite. The creation of this nanostructured formation's growth phenomenon was subsequently explained by a surface diffusion mechanism. According to the X-ray diffraction results, the iron oxide nanoleaf was Fe3O4 and α -Fe2O3 after the oxidation. The dimension of the nanoleaf was found to be 20-60 nm and lengths up to 1 µm. These dimensions are dependent on the oxidation temperature. The activation energy on the crystallographic plane and grain boundary has an impact on how nanostructures grow during oxidation

SYNTHESIS AND CHARACTERIZATION OF IRON OXIDE NANOLEAF BY THERMAL OXIDATION

In this work, a simple method for the efficient and rapid synthesis of onedimensional hematite (α-Fe2O3) nanostructures is proposed based on a thermal oxidation approach. This technique is to create iron oxide nanoleaf on the iron (Fe) substrate. The oxidation was done at three different temperatures (200-600 oC) by oxidizing the Fe foils in a chamber furnace. The low temperature thermal oxidation at 400 oC for 2 h resulted in the formation of hematite iron oxide with good nanoleaf coverage on the foil surface. The obtained nanostructures physical and structural characteristics were characterize using XRD, and Raman spectroscopy. While their morphological characteristics were observed using the FESEM. It was discovered that when the oxidation period lengthened, the peak intensities in relation to the hematite increased. The duration of heating has a substantial impact on the development and ultimate morphology of hematite. The creation of this nanostructured formation's growth phenomenon was subsequently explained by a surface diffusion mechanism. According to the X-ray diffraction results, the iron oxide nanoleaf was Fe3O4 and α -Fe2O3 after the oxidation. The dimension of the nanoleaf was found to be 20-60 nm and lengths up to 1 µm. These dimensions are dependent on the oxidation temperature. The activation energy on the crystallographic plane and grain boundary has an impact on how nanostructures grow during oxidation