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- ItemThe improvement of diamond‑like carbon coatings for tribological and tribo‑corrosion applications in automobile engines: an updated review study(Springer, 2023-03-21) Funsho Olaitan Kolawole; Olawale Samson Kolade; Sefiu Adekunle Bello; Shola Kolade Kolawole; Aduramigba Toluwani Ayeni; Temidayo Foluso Elijah; Sunday Gbenga Borisad; André Paulo TschiptschinDiamond-like carbon (DLC) coatings have gained wide attraction, due to ultra-low coefficient of friction, high resistance to wear, excellent mechanical properties, and inert to chemical substance, especially in the automobile industry in the last decade. However, a lot of research is still carried out to improve the adhesion properties of DLC coatings to metallic substrate to prevent debonding caused mostly by high internal compressive stress and the difference in thermal expansivity between the metallic substrate and the DLC coatings. Consequently, to improve the adhesion of DLC coatings on metallic substrate, the use of interlayers (Si, SiH and Cr, CrN, Ti and TiN) and metallic (Mo, Ti, Cr, and W) and non-metallic (Si, N, and F) doping elements has been put to use. The interlayers form a transition layer between the metallic substrate and the DLC coating, thereby reducing the thermal expansivity between the metallic substrate and the DLC coatings. On the other hand, the metallic and non-metallic doping elements help in reducing the internal compressive stress in the DLC coatings. The present review article focuses mainly on the deposition techniques, characterisation techniques, and improvement of the adhesion properties of DLC coatings on metallic substrates. It showcases Cr-based interlayers and W/WC dopants as an efficient way to improve adhesion properties of DLC coatings for tribological and tribo-corrosion application in the automobile industry.
- ItemFracture toughness of duplex CrN/DLC and nano-multilayer DLC-W deposited on valve tappet via hybrid PVD and PECVD(Springer, 2024-04-04) Funsho Olaitan Kolawole; Shola Kolade Kolawole; Sefiu Adekunle Bello; Shedrack Yakubu; Oluwole Daniel Adigun; Adebayo Felix Owa; Reginald Umunakwe; Abdullahi Olawale Adebayo; Chioma Ifeyinwa MaduekeDLC coatings are well known for their high fracture toughness, however, often exhibit poor adhesion properties on metallic substrates. The use of interlayers and metallic doping can be used to overcome such challenge. In this study duplex CrN/DLC and nano-multilayer DLC-W coatings were both deposited on hydraulic valve tappet using a hybrid PVD/PECVD deposition system. Microhardness measurements were taken for the uncoated valve tappet, duplex CrN/DLC and nano-multilayer DLC-W coated valve tappet at loads of 0.98 N, 1.96 N, 2.94 N, 4.9 N, 9.8 N and 19.6 N for 15 seconds using a Shimadzu hardness tester. The fracture toughness was evaluated using the Vickers indentation method from microhardness indents on the surface of the coatings. The fracture toughness for duplex CrN/DLC and nano-multilayer DLC-W coatings indented at 4.9 N, 9.8 N and 19.6 N, reveals that the fracture toughness for the duplex CrN/DLC were 20.24 ± 0.97 MPa.m1/2, 17.18 ± 0.86 MPa.m1/2 and 6.6 ± 0.28 MPa.m1/2 respectively. While the fracture toughness for nano-multilayer DLC-W was calculated as 3.75 ± 0.41 MPa.m1/2 and 4.67 ± 0.38 MPa.m1/2 at 9.8 N and 19.6 N respectively.
- ItemEggshell nanoparticle reinforced recycled low-density polyethylene: A new material for automobile application(Elsevier, 2021-05-07) Sefiu Adekunle Bello; Nasirudeen Kolawole Raji; Maruf Yinka Kolawole; Mohammed Kayode Adebayo; Jeleel Adekunle Adebisi; Kehinde Adekunle Okunola; Mustekeem Olanrewaju AbdulSalaam
- ItemMicrostructure and mechanical properties of Al0.44Si0.32Ni0.09Fe0.05V0.05 alloy containing nanosilica for vehicle bonnet applications(Elsevier, 2025-01-25) Sefiu Adekunle Bello; Maruf Yinka Kolawole; Raphael Gboyega Adeyemo; Funsho Olaitan Kolawole; Uthman Ayomide Aliu; Ayodeji Aboyeji; Ahmed Rafiu; Abdul Ganiyu Funsho Alabi; Oyetunji AkinlabiStringent conditions of service that demand improved properties spurs continuous research on expired products to emerge new materials for engineering applications. An alloy was developed from aluminium scraps, ferrosilicon, and nickel alloy. The developed alloy was modified by nanosilica and the produced materials were examined. Result displays silica having an average size of 63.76 nm. In addition, new phases were detected in the alloys due to nanosilica additions and heat treatment. Moreover, the threadlike grain boundary phases of the control alloy changed to rounded tiny particles after the heat treatment. Silica addition to the alloy caused refinements of grains leading to numerous grain boundaries while the grain boundary phases of the heat treated nanosilica modified alloy appear in form of a modulated featherlike structure. An improvement in tensile strength was noted up to 10 wt% of nanosilica additions. Reduction in the impact energy prevails above 6 wt% of nanosilica addition. Heat treatment enhanced tensile properties and impact energies but reduced the hardness values of the developed alloys. Moreso, linear response surface models are significant in predicting the tensile strengths of the developed alloys. Model diagnostics like outlier and Cook’s distance confirm no error in the models. Comparation of properties affirms that tensile strength, tensile strain, and impact energy of the heat treated Al0.44Si0.32Ni0.09Fe0.05V0.05 alloy containing 10 wt% of nanosilica are greater than those of the LEXUS LX570 (2018 model), TOYOTA HILUX (2017 model), and TOYOTA CAMRY (2018 model). Hence, it is a strong, ductile, tough, and less hard material for the bonnet applications.
- ItemWear resistance properties of particles‑reinforced epoxy nanocomposites using historical data response surface models(Springer, 2023-08-30) Sefiu Adekunle Bello; Raphael Gboyega Adeyemo; Abdul Ganiyu Funsho Alabi; Maruf Yinka Kolawole; Sadam Oniwa; Azim Bayonle Kareem; Muizz Oyeleye Azeez; Bunmi Bisola Olaiya; Tosin Adewale Salami; Sofiu Oladimeji Abdulkareem; Quamdeen Aremu Lawal; Kabir Omoniyi Mohammad; Peter Akinola Akindahunsi; Johnson Olumuyiwa Agunsoye; Suleiman Bolaji HassanKnowledge of wear resistance properties of newly emerging materials as complements to their mechanical properties is important to broaden their applications. This study focuses on wear resistance properties of particle-reinforced epoxy. Results obtained reveal that surface wear of the examined epoxy-based composites occurred by the crack initiation by the abrasive tips of the wear tester, crack propagation and/ or crack pinning. Linear regression model has accuracies of 99.94, 99.92, 99.93, 99.88, 99.91 and 99.92% with respect to various grades of composites examined. Response surface two-functional interaction model exhibits a better goodness of fit than the response surface linear model that shows an outlier. The response surface linear model best fits the wear rates of AlnpUCSnp/epoxy and AlnpCCSnp/epoxy with respective adequate precision of 14.138 and 10.204 affirming the model’s adequate signal. Hence, this study establishes that epoxy-based hybrid composite having 4.7%–82.47 nm-sized aluminium-5.76%–49.85 nm-sized carbonised coconut shell hybrid particles experiences a surface wear of 0.00272721 g per metre when it is in contact with a rough surface under an applied load of 16.71 N at a speed of 0.7 ms−1.