Corrosion Resistance, Evaluation Methods, and Surface Treatments of Stainless Steels

Stainless steels are widely recognized and find applications in many engineering industries and companies due to their excellent properties including high resistance to corrosion as a result of their minimum 10.5% chromium content, exceptional strength and durability, temperature resistance, high recyclability, and easy formability. In the present book chapter, the basic concepts of stainless steel including its applications, classifications, and corrosion properties will first be discussed. Thereafter, their corrosion behaviour will then be explained. The various methods by which the corrosion resistance behaviour can be significantly improved including surface treatments such as coatings/electrodepositions, alloying, mechanical treatment, and others will be discussed in detail

Economics, Sustainability, and Reaction Kinetics of Biomass Torrefaction

Biomass torrefaction is capable of significantly improving the quality and properties of solid biofuels. It is often referred to as complex reactions involving the decomposition of lignin, cellulose, and hemicellulose as well as moisture evaporation due to several reactions involved. To evaluate the efficiency of the torrefaction process as well as the reactor performance, considering the economics of biomass torrefaction including the total production cost and capital investment, production capacity, feedstock input, feedstock type, pre-treatment, procurement and transportation costs is of high importance. In this Chapter, the economics of torrefaction process will be discussed. In addition, ways to ensure competitiveness of torrefaction technology will be explained provided factors including the use of plant with larger capacity, integrated system features such as pelletization, and moisture content of the feedstock, are properly considered. Thereafter, the concept of sustainability of biomass torrefaction in relation with the environmental factor (sustainable forest management), social factor (revitalization of rural areas), and economic factor (fossil fuels dependence and renewable energy consumption) will be presented

Corrosion resistance of surface-conditioned 301 and 304 stainless steels by salt spray test

The corrosion rate of surface-conditioned 301 and 304 stainless steels (SS) was determined by salt spray test in a controlled accelerated corrosive medium (9.5 L of pure distilled water + 500 g NaCl). By surface conditioning via mechanical attrition treatment, a gradient-structured layer was firstly generated on the surface of the samples before the salt spray test. The corrosion rate was determined by the weight loss before and after the salt spray test. Compared to the untreated 301 SS sample with a weight loss of 0.15 g, the surface-conditioned samples treated for 300 s and 1200 s experienced a lower weight loss of 0.04 and 0.02 g, respectively. A similar reduction in weight loss was achieved for 304 SS sample when treated for 5, 10, and 20 mins

Corrosion resistance of surface-conditioned 301 and 304 stainless steels by salt spray test

The corrosion rate of surface-conditioned 301 and 304 stainless steels (SS) was determined by salt spray test in a controlled accelerated corrosive medium (9.5 L of pure distilled water + 500 g NaCl). Surface conditioning via mechanical attrition treatment was firstly carried out before the salt spray test. The corrosion rate was determined by weight loss method before and after the salt spray test. Compared to the untreated 301 SS sample with a weight loss of 0.15 g, the surface-conditioned 301 SS samples treated for 300 s and 1200 s experienced a lower weight loss of 0.04 and 0.02 g, respectively. A similar reduction in weight loss was achieved for 304 SS sample when treated for 300, 600, and 1200 s

Simulation-based analytical design for aluminium recycling processing plant

Indiscriminate disposal of beverage cans as waste poses a great threat to the environment, causing flooding, landfill, and blockage of drainages, leading to land pollution and sometimes accident. Hence, there is a need to design a system capable of converting these wastes into usable products. In this study, a simulation-based analytical design for aluminium recycling processing plant was carried out to ascertain the efficiency and reliability of the design before fabrication using finite element analysis (FEA) approach. The simulation results revealed a lesser maximum stress of 6.323 MPa for the furnace outer casing under the action of load with a displacement of 0.0795 mm. The stress of the machine components is less than the yield strength of the selected materials, making the machine fit and workable. The analytical results agree with the numerical analysis; hence the conceptual design is fit for fabrication based on the design analysis and evaluation. After the design analysis and simulation, the designed recycling process plant parts are found to be under negligible deflection and stress which is far below the yield strength of chosen materials

Evaluating the impact of recycling on polymer of 3D printing for energy and material sustainability

This research explores the sustainability of recycling polymer composites using fused deposition modelling (FDM). The objective was to assess how different recycling cycles affect the mechanical integrity and energy efficiency of recycled polymers. The study employed quantitative assessments of tensile strength, energy consumption, and carbon emissions across multiple recycling cycles. Recycled materials were compared with virgin materials to establish a baseline for degradation and efficiency. Various additives were tested to evaluate their ability to stabilise material properties. Significant findings indicate that recycled polymers retain up to 90 % of their original tensile strength after the first cycle, declining to 80 % after three cycles. Energy usage during the recycling process decreased by 30 %, while the carbon footprint was reduced by 25 %, showcasing notable environmental benefits. The study confirms that FDM recycling of polymer composites can be optimised to achieve substantial sustainability benefits in terms of environmental impact and material preservation

Simulation-based analytical design for aluminium recycling processing plant

Indiscriminate disposal of beverage cans as waste poses a great threat to the environment, causing flooding, landfill, and blockage of drainages, leading to land pollution and sometimes accident. Hence, there is a need to design a system capable of converting these wastes into usable products. In this study, a simulation-based analytical design for aluminum recycling processing plant was carried out to ascertain the efficiency and reliability of the design before fabrication using finite element analysis (FEA) approach. The simulation results revealed a lesser maximum stress of 6.323 MPa for the furnace outer casing under the action of load with a displacement of 0.0795 mm. The stress of the machine components is less than the yield strength of the selected materials, making the machine fit and workable. The analytical results agree with the numerical analysis; hence the conceptual design is fit for fabrication based on the design analysis and evaluation. After the design analysis and simulation, the designed recycling process plant parts are found to be under negligible deflection and stress which is far below the yield strength of chosen materials

Superior strength and wear resistance of mechanically deformed High-Mn TWIP steel

In the present study, the mechanical and wear behaviour of the surface-mechanically treated high-manganese (high-Mn) twinning-induced plasticity (TWIP) steel were investigated. The TWIP alloy was first designed and fabricated via surface-mechanical attrition treatment (SMAT) system and the mechanical properties including strength, wear behaviour as well as the microstructural evolution were thereafter determined. Transmission electron microscopy (TEM) characterization revealed a typical dislocation as a result of the surface treatment as well as the formation of twin layers with a reduced stacking fault energy (SFE). Due to the ultra-fine grain refinement caused by plastic deformation during surface treatment, a microhardness value of 489 HV can be obtained after treatment. Likewise, the yield strength of the high-Mn TWIP steel could be enhanced from 360 MPa to 813 MPa and a reduction in elongation to failure of about 20 % can be achieved. The wear test showed that the treated TWIP steel possessed a reduced friction coefficient and improved wear resistance at different testing loads, attributed to the nanoscale refinement of grains induced during treatment. The strength, hardness, and wear resistance of the fabricated TWIP alloy improves significantly, thanks to surface treatment by SMAT.</p

Strengthening and precipitation hardening mechanisms of surface-mechanically treated 17-4PH stainless steel

Achieving ultra-high strength without sacrificing too much ductility is the focus of attention in nanostructured materials. Here, the strengthening mechanism and property enhancement of surface-mechanically treated 17-4PH stainless steel (SS17-4PH) were investigated. Our findings show that a grain refinement and elongated lath-like martensitic grain (~ 50 nm thick) could be produced after surface treatment. The grain size remains in the nanoscale, and random crystallographic orientations with the presence of nanocrystallites characterize the nanocrystalline grains formed on the treated sample. This contributes to the property enhancement with a yield strength of about 901 MPa and a reduced elongation to failure of about 17%. The atom probe tomography (APT) characterization unveiled the emergence of high-density precipitate (Cu-rich) at the material surface, with a number density of about 2.6255 × 1024 m−3 and an average radius of 2.22 nm. Besides, the dislocation activities caused by SMAT result in the gradual breakdown of precipitates into smaller sizes and final dissolution in the matrix, increasing the number of nucleation sites and leading to more grain refinement processes. The grain boundary, dislocation densities, and the Cu-rich precipitate greatly influence the strengthening mechanism of surface-treated SS17-4PH.</p

Solid Biofuel Production from Biomass:Technologies, Challenges, and Opportunities for Its Commercial Production in Nigeria

Producing durable and efficient solid biofuels should be an important consideration in Nigeria’s present economy due to the numerous advantages associated with it. It offers the benefit of energy generation, particularly in rural areas, and could potentially replace fossil fuels. However, the adoption and production of solid biofuels at commercial scale in Nigeria is limited by some challenges, including the lack of a developed supply chain structure, inadequate facilities, and air pollution. The present study summarizes the types of solid biofuel production technologies deployed in Nigeria as well as the biomass feedstock utilized in the production of fuel briquettes and pellets. While opportunities exist in the gasification of biomass in Nigeria, direct combustion is a readily applicable fuel conversion process that can be utilized to generate electricity from solid biofuel. The major challenges surrounding the full adoption of solid biofuel production and utilization in Nigeria are highlighted. Among others, promotion of clean energy alternatives, investments and financial incentives, sustainable renewable energy policy and energy transition plan, and legislative backing are identified as factors that could accelerate the commercial production and adoption of solid biofuel in Nigeria