Corrosion and Degradation of Materials

Studies on the corrosion and degradation of materials play a decisive role in the novel design and development of corrosion-resistant materials, the selection of materials used in harsh environments in designed lifespans, the invention of corrosion control methods and procedures (e.g., coatings, inhibitors), and the safety assessment and prediction of materials (i.e., modelling). These studies cover a wide range of research fields, including the calculation of thermodynamics, the characterization of microstructures, the investigation of mechanical and corrosion properties, the creation of corrosion coatings or inhibitors, and the establishment of corrosion modelling. This Special Issue is devoted to these types of studies, which facilitate the understanding of the corrosion fundamentals of materials in service, the development of corrosion coatings or methods, improving their durability, and eventually decreasing corrosion loss

Plasma spray of nicraly coating on laser surface modified H13 tool steel

This thesis presents experimental study of nickel-based alloy, NiCrAlY coating on laser modified AISI H13 steel using atmospheric plasma spray (APS). AISI H13 steel is often being used as die material in metal forming technology, specifically semi solid metal processing. Repetitive process of incoming high temperature, solidification and rapidly quenched semi solid metal through die, causes erosion and corrosion wear on the die cavity surface. Erosion which was causes by friction and corrosion by chemical reaction mitigate die performance and durability properties. Hence, retaining die properties were crucial to gain optimum semi solid metal processes. This study aims to modify AISI H13 steel substrate surface for enhanced mechanical properties and interfacial bonding with NiCrAlY coating. Mechanical properties of AISI H13 steel surface micro hardness was enhanced from rapid quenching process by pulse laser surface modification. While, interfacial bonding of NiCrAlY coating was enhanced by increasing the percentage of chemical elemental diffusion and the surface roughness asperities for mechanical interlocking. A modified layer of AISI H13 steel with enhanced surface properties was developed using two different laser spot size of 90 µm and 600 µm separately. The mechanical properties and interfacial bonding of NiCrAlY coating on laser surface modified AISI H13 steel substrate were enhanced at different laser parameters. Laser parameters of 90 um spot size used were laser peak power; 0.76 kW and 1.3 kW, pulse rate frequency (PRF); 2500 Hz and 2800 Hz and laser scanning speed; 2.0 mm/s and 6.0 mm/s. While, laser parameters of 600 um spot size used were laser peak power; 1.6 kW and 2.0 kW, pulse rate frequency (PRF); 40 Hz and 60 Hz and laser scanning speed; 14.13 mm/s and 20 mm/s. Prior to NiCrAlY coating, lasered samples being modified by 600 um laser spot size went on sandblasting process. Surface profile such as asperities, valleys depth and peak height and average roughness, Ra also had been analyzed. Asperities at the entire surface profile with low peaks and valleys size promotes wettability of coating particle splats during coating. Elemental analysis showed chemical bonding occurred in coating because of element diffusion. Metastable phase occurred on the laser modified surface inspired atomic diffusion that enhanced coating adhesion. Metastable phase consists of excited energy that promotes atomic diffusion between the laser modified/coating interlayer. Results for coating interfacial toughness obtained by Vickers interfacial indentation test (IIT) were obtained above reference sample toughness measurement which was 2.08 MPa. Interfacial toughness range between 2.02 to 6.54 MPa. For conclusion, interface bonding of NiCrAlY coating is enhanced based from the research objectives. Mechanical interlocking plays an important role for interface bonding of NiCrAlY coating. Surface that contains asperities at whole surface profile, decreasing depth and peaks measurement increased coating adhesion. For atomic bonding, metastable α-Fe phase occurs from laser surface modification assists atomic diffusion in the NiCrAlY coating interlayer. Mechanical interlocking plays major role in the succesful of the NiCrAlY coating adhesion. Hence, NiCrAlY coating on laser modified H13 steel by 600 um laser spot size requires surface post processing using sandblasting. This research findings were important to obtained achievement of coating layer with resistance to erosion and corrosion in the direction of manufacturing sustainability

Flat-plate solar array project. Volume 5: Process development

The goal of the Process Development Area, as part of the Flat-Plate Solar Array (FSA) Project, was to develop and demonstrate solar cell fabrication and module assembly process technologies required to meet the cost, lifetime, production capacity, and performance goals of the FSA Project. R&D efforts expended by Government, Industry, and Universities in developing processes capable of meeting the projects goals during volume production conditions are summarized. The cost goals allocated for processing were demonstrated by small volume quantities that were extrapolated by cost analysis to large volume production. To provide proper focus and coverage of the process development effort, four separate technology sections are discussed: surface preparation, junction formation, metallization, and module assembly

Silicon-on ceramic process: Silicon sheet growth and device development for the large-area silicon sheet task of the low-cost solar array project

The technical feasibility of producing solar-cell-quality sheet silicon to meet the Department of Energy (DOE) 1986 overall price goal of $0.70/watt was investigated. With the silicon-on-ceramic (SOC) approach, a low-cost ceramic substrate is coated with large-grain polycrystalline silicon by unidirectional solidification of molten silicon. This effort was divided into several areas of investigation in order to most efficiently meet the goals of the program. These areas include: (1) dip-coating; (2) continuous coating designated SCIM-coating, and acronym for Silicon Coating by an Inverted Meniscus (SCIM); (3) material characterization; (4) cell fabrication and evaluation; and (5) theoretical analysis. Both coating approaches were successful in producing thin layers of large grain, solar-cell-quality silicon. The dip-coating approach was initially investigated and considerable effort was given to this technique. The SCIM technique was adopted because of its scale-up potential and its capability to produce more conventiently large areas of SOC

Obtaining and Characterization of New Materials

At present, more and more procedures and technologies used to discover and characterize new materials are available, including advanced characterization techniques.This Special Issue covers a wide range of topics about obtaining and characterizing new materials, from the nano to macro scales, including for new alloys, ceramics, composites, biomaterials, and polymers and the procedures and technologies used to enhance their structure, properties, and functions. To select new materials for future use, we must first understand their structure and their characteristics using modern techniques such as microscopy (SEM, TEM, AFM, STM, etc.), spectroscopy (EDX, XRD, XRF, FTIR, XPS, etc.), and mechanical tests (tensile, hardness, elastic modulus, toughness, etc.) and their behaviors (in vitro and in vivo; corrosion; and thermal—DSC, STA, DMA, magnetic properties, and biocompatibility), among many others