The goal of this work is comparative study of lubricants with different content of nanoparticle additive to obtain material with an optimal tribological properties. Design/methodology/approach: The effects of carbon nanotube (CNT) and Si3N4 nanoparticle additives on the lubricated friction and wear behaviour of AISI 4140 steel were investigated. In tribological tests, the amounts of nanoparticles added to base oil (SAE 10W40) were varied. The ball-on-disc configuration of the tribometer was used for wear testing (DIN 50324). Specific wear rate, coefficient of friction, wear scar depth were measured. The wear surfaces were analysed using scanning electron microscopy and surface profilometer. Findings: Results showed that with the addition of nanoparticles, wear rates of AISI 4140 steel were decreased. The best additive content of synthetic oil was 0.05% CNT + 0.05% Si3N4 (mass fraction), and in this case, the friction coefficient and the wear rate were decreased 15.2% and 76.4%, respectively. Research limitations/implications: Obtained lubricants are characterized by tribological and frictional properties but homogeneity of lubricants should be improved because of agglomeration. Farther works will be continued also for different contents of lubricant. Practical implications: Tested lubricants can be applied among in industry where wear and friction properties are important. Originality/value: Nanoparticle additive oils which have excellent tribological properties can be very attractive for automobile industry. New type of lubricant mixture (CNT and Si3N4) is used in the paper.
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Purpose: This study aims to investigate the fatigue life of box borided AISI 1010 steel materials. Design/methodology/approach: Fatigue specimens firstly have been prepared according to ASTM E466-96 standard and normalized. Then their surfaces have been cleaned by polishing. Boriding heat treatment has been applied in solid media with the help of Ekabor2 powder. Specimens have been borided at 1173-1223-1273 and 1323 K temperatures for 2-4 and 6 hours respectively. Fatigue tests have been made in rotating-bend test device. Separate S-N diagram has been formed for each boriding condition and then their results were compared with the results of the specimens on which any heat treatment has not been made. Findings: As a result it has been seen that boriding has no positive effect on fatigue life of AISI 1010 steel materials. And also it has been determined that fatigue life of the materials on which boriding heat treatment applied, decreases in between 14 %-55 %. Research limitations/implications: It can be noted that the reasons of short fatigue life determination are the boride layer’s much higher hardness than the substrate material’s, and the micro cracks existed between boride phases formed onto the surface. Originality/value: The investigations on fatigue life of borided AISI 1010 steel were made.
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