Search

Sulphuric acid (H2SO4) is widely used in various industrial processes, including fertilizer production. However, its highly corrosive nature poses a significant challenge to the materials used for transport and storage, particularly metals and alloys. This review provides an overview of corrosion types in iron and nickel-based alloys, commonly employed for handling sulphuric acid. The paper discusses alloy selection based on their corrosion behavior in different H2SO4 concentrations, temperatures, and harsh conditions such as erosion-corrosion and presence of contaminants. Additionally, it highlights the use of inhibitors and polymeric coatings for corrosion protection. Finally, the paper outlines future research directions for corrosion protection of alloys in sulphuric acid environments.

Wear (erosion/abrasion) and corrosion act in synergy in several industrial installations where corrosive fluids circulate together with a solid phase causing mutual damage. High entropy alloys (HEAs) are promising materials to be used in that type of environments because of their outstanding chemical, electrochemical and mechanical properties. While several review articles are currently available on corrosion, mechanical properties, development of HEAs, microstructure, and HEA coatings, there is an undeniable lack of a comprehensive and critical review focusing on the tribological behaviour and tribocorrosion of bulk HEAs. This work aims to collect, summarise, and critically review the major accomplishments and progresses of HEAs over the last 20 years dealing with wear, corrosion, and wear-corrosion resistance. It highlights the most significant aspects that can influence the performance of HEAs including the change of the base alloying elements, the influence of the temperature, heat treatment, and wear test parameters (load, velocity, duration, distance). Furthermore, operating mechanisms, together with the relationship between microstructure and wear resistance, and between microstructure and corrosion resistance will be described. Finally, the articles that have been reported in the literature dealing with tribocorrosion of HEAs will be reviewed. The results of this study are expected to guide potential researchers and provide them with the sum of current trends in HEAs in terms of corrosion resistance, wear resistance and the synergy of both, in the hope of helping them to make the right decision to design and develop new HEAs or improve the research on the existing ones.

This study aims at understanding the effect of different heat treatments on the evolution of the microstructure of several Cr–W–V–Mo steels having different compositions and how this latter affects their abrasion resistance. The investigation also gives insights on the formation and effect of core-shell carbides on the abrasion resistance. The commercial highly alloyed stainless steel HCx® and six newly designed Cr–W–V–Mo steels were subjected to three heat treatments: austenitizing at 900 °C and 1100 °C and subsequent quenching, and an ageing treatment at 700 °C. The microstructural analysis demonstrated the formation of Laves phase when austenitizing at 900 °C; this phase is depleting the matrix from carbide forming elements without any improvement in the wear behavior of the alloys. However, increasing the austenitization temperature to 1100 °C favored the development of core-shell carbides that contribute to increase the abrasion resistance of the alloys. The ageing treatment promoted the precipitation of secondary carbides uniformly distributed along the matrix, and they were found to have a beneficial effect on maintaining the good abrasion resistance even after subjecting the steels to a high ageing temperature (700 °C) for long duration (10 h).

The wet phosphoric acid (WPA) process equipment is exposed to corrosive and wear conditions with aggressiveness determined by the phosphate rock chemical composition and process parameters employed. Stainless steels and nickel alloys are attractive materials considered for WPA plant construction since they are mechanically and chemically robust to withstand the aggressive environment encountered. This review first describes the WPA process emphasizing on the aggressiveness of the environment to plant construction materials. Then, principles behind design and fabrication of stainless steels and nickel alloys with properties tailored to withstand this aggressive environment are described. To withstand corrosion conditions encountered during the WPA process alloys should contain sufficient chromium (Cr), with some molybdenum (Mo) and nickel (Ni) contents and should possess a homogeneous microstructure. Wear resistance in a specific section of the plant is ensured by adjusting the carbon content and carbide formers contents to obtain adequate carbides for protection from abrasion. Reported data on deterioration rates and failure mechanisms of commonly used alloys is first presented before discussing selection and performance of these alloys in different sections of the WPA plant. Future challenges and opportunities in selection of suitable materials and development of novel materials are finally outlined.

There is a huge demand for high-performance materials in extreme environments involving wear and corrosion. High chromium white cast irons (HCWCIs) display better performance than many materials since they are of sufficient hardness for wear protection and can be tailored in chemical compositions to improve corrosion resistance; however, their performance is often still inadequate. This article reviews the chemical composition and microstructure design aspects employed to tailor and develop HCWCIs with combined corrosion and wear resistance. The performance of these alloys under wear and corrosion is reviewed to highlight the influence of these parameters in the industry. Existing challenges and future opportunities, mainly focusing on metallurgical alloy development aspects like chemical composition, casting, and heat treatment design, are highlighted. This is followed by suggestions for potential developments in HCWCIs to improve the performance of materials in these aggressive environments. Many variables are involved in the design to obtain suitable microstructures and matrix composition for wear–corrosion resistance. Computational modeling is a promising approach for optimizing multi-design variables; however, reliable field performance data of HCWCIs in wear–corrosion environments are still inadequate. Quantitative evaluation of the wear–corrosion performance of HCWCIs requires the development of laboratory and field tests using standard conditions like abrasive type and sizes, severity of loading, slurry velocity, pH, and temperature to develop wear–corrosion maps to guide alloy development.

This work presents a mathematical tool to estimate the cost of fabricating pumps by traditional casting. The drivers that most affect the cost of the process are identified in each step of the procedure, i.e., material, labour, energy, tools and general expenses associated with any industrial activity. The mathematical expressions used for the calculation of the different cost drivers are presented and used to estimate the cost of fabricating the different parts composing a radial pump in a small Moroccan foundry. Therefore, the input data of the equations carefully consider the economic factors of this country. However, the developed tool is versatile and can be adapted to describe the casting process in other countries with different economies just by changing the input data accordingly. It is observed that the influence of the drivers in the final cost of the pump is very dependent on the number of pumps to be produced. In any case, the cost estimation tool presented in this work will allow for the optimization of the yield of the casting process rendering the involved company more reliable. The tool provides an idea of the implications of changing production factors, allowing the foundry to give accurate and fast responses without compromising its profits.