ORIGINAL PAPER Tribological Investigation of AZ91/SiC Magnesium Hybrid Composite under Dry, Oil and Nanofluids Lubricating Conditions Sandeep Singh Kharb 1 & Sandeep Kumar Khatkar 2 & Abhishek Charak 3 & Archana Thakur 2 Received: 8 December 2019 /Accepted: 13 May 2020 # Springer Nature B.V. 2020 Abstract In present research AZ91D/SiC composites were developed using advanced vacuum assisted stir casting process. The tribolog- ical properties of AZ91D/SiC composites under dry, oil and nanofluids lubricating conditions were investigated. The nanofluids were prepared by adding the silicon carbide (SiC) nanoparticles to the soluble oil with different weight percentages (1 wt.%, 1.5 wt.%, 2.0 wt.%) for experimentation. The mixing of nanoparticles with base fluid improves the tribological and thermal properties of fluids as the nanoparticles possess higher thermal conductivity than base fluids. The thermal conductivity of SiC nanofluids was evaluated. The wear surfaces under different lubricating conditions (dry, oil and nanofluids) were also analyzed with FESEM. The findings of the study reveal that there was a remarkable enhancement in tribological properties (wear and coefficient of friction) when SiC nanoparticles were added to soluble oil. Furthermore, the selected samples were analyzed using energy-dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM). Keywords AZ91D/SiC composites . Nanofluids . Co-efficient of friction . Wear . Thermal conductivity 1 Introduction Magnesium is the third-most-commonly-used structural met- al, following iron and aluminium. Magnesium, having density 2/3rd of aluminum, and 1/3rd of steel with high specific strength and stiffness has emerged out as an important material for light weight applications in automobile and aerospace industries [1]. High purity, AZ91D is the most used magnesium alloy for structural applications in automobile industries because of good castability, machinability, corrosion properties and high specific strength. But due to low creep resistance and wear resistance limits its wider applications. To counter these limitations, researchers added micro and nano size reinforcement in AZ91D to form metal matrix composites (MMCs). The different reinforcement such as TiC [2], SiC [3], B 4 C[4], TiB 2 [ 5 ], Si 3 N 4 [ 6 , 7 ] Oxides Al 2 O 3 [ 8 ],Y 2 O 3 [ 9 ], Carbonous particles CNTs [10], carbon nanoparticles [11] graphene [12, 13] and solid lubricant such as graphite [14], Mos 2 [15] have been added by researchers to enhance mechanical and tribological properties of AZ91D. Researchers claimed that SiC having high strength, melting point and lighter than other ceramics has emerged out suitable reinforcement for magnesium and its alloys [16]. Researchers found that the creep, tensile, impact, hardness and wear resistance of AZ91D alloy improved significantly by reinforcing different size of SiC particles [17, 18]. The wear properties of AZ91D alloy under dry condition were investigated by various researchers. In this regard, Girish et al. [19] identified that the wear rate with SiC particle– reinforced composites was less than the unreinforced alloy specimens. Daniel et al. [20] also claimed that the wear rate of AZ91D alloy with SiC particle–reinforcement was less compared to AZ91D alloy. Huang et al. [21] discussed the wear behavior of AZ91D alloy and AM60B alloy. Authors found that AZ91D alloy shows less co-efficient of friction and wear as compared to the AM60B alloy. Chen et al. [22] discussed the influence of process parameters on wear behav- ior of AZ91D magnesium alloys. Authors identified that the process parameters does not change the dominative wear whereas the wear rate is affected by the process parameters * Sandeep Kumar Khatkar sandeep.4388@cgc.edu.in 1 Poornima Institute of Engineering and Technology, Jaipur, India 2 Chandigarh Engineering Colleges, Landran, Mohali, India 3 Punjab Engineering College (Deemed to be university), Chandigarh 160012, India Silicon https://doi.org/10.1007/s12633-020-00520-3