Browsing by Author "Parthasarathi, N.L."

Filter results by typing the first few letters
Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Effect of thermal expansion on the high temperature wear resistance of Ni-20%Cr detonation spray coating on IN718 substrate
    (Elsevier B.V., 2023) Purushotham, N.; Parthasarathi, N.L.; Babu, P.S.; Govindarajan, G.; Rajasekaran, B.
    The temperature-dependent materials properties on the dry sliding wear resistance of the detonation sprayed Ni-20%Cr coating have been studied. In-situ high-temperature X-ray diffraction (HT-XRD) was used to investigate high-temperature properties such as stress relieving, recrystallization, and thermal expansion. The dry sliding wear test was performed by using a ball-on-disc tribometer by sliding velocities (0.1 m/s), varying loads (6 N and 10 N), and temperatures (25 °C and 850 °C) against alumina (Al2O3) ball. The phase evolution, thermal expansion, crystallite size, and lattice strain were determined by the Williamson-Hall method. Field emission scanning electron microscopy and a non-contact optical profilometer was used to characterize the wear scar and calculate the wear rate. The wear test results demonstrated that the as-deposited coatings coefficient of friction (CoF) and wear rate (ω) continuously decreased as the temperature increased. The primary wear mechanism changed from abrasive and surface fatigue to adhesive and oxidative wear. The impact of stress relieving, recrystallization, and forming a composite tribolayer (Cr2O3, NiO) at elevated temperatures reduced the friction and enhanced the wear resistance. The effect of stress relieving, recrystallization, thermal expansion, and oxidation on the wear resistance of the coating has been discussed with a suitable mechanism. © 2023 Elsevier B.V.
  • No Thumbnail Available
    Item
    Evaluation of the Loss of Surface Roughness Following the Use of Four Different Instruments for Mechanical Debridement of Dental Implants: An In-vitro Pilot Study
    (Springer Science and Business Media Deutschland GmbH, 2024) Kumar, S.; Yewale, M.; Parthasarathi, N.L.; Balasundaram, R.; Gopalkrishna, P.; Bhat, S.G.
    To compare the dental implant surface properties such as mean surface roughness, roughness depth, and the surface loss produced by different prophylactic instrument types. Twenty-four surfaces of twelve dental implants were treated using titanium curettes, titanium-coated curettes, an air abrasion unit, and titanium brushes. The dental implants were inserted partially into a Styrofoam base, exposing one-third to simulate cases of peri-implantitis. The exposed surface was coated with artificial dental calculus (ADC) and divided into four groups for treatment. The arithmetic mean surface roughness (Ra) and the mean roughness depth (Rz) were assessed using the confocal microscope, and the surface loss (SL) area was calculated from the scanning electron microscopic images using an image analysis software. The Ra value varied between 1.08 to 0.29 µm, the Rz value between 10.3 to 70.5 µm, and the mean surface loss area between 154 to 9410 µm2. The One-way ANOVA analysis showed a statistically significant difference between the four groups (P < 0.05). The air abrasion unit showed the highest mean roughness value of 1.08 ± 0.14 µm, mean roughness depth of 70.5 ± 2.21 µm, and a minor surface area loss of 154 ± 132 µm2. In comparison, the titanium brushes showed the least Ra and Rz of 0.29 ± 0.05 µm and 10.3 ± 2.32 µm, respectively, whereas the titanium-coated curettes showed the highest loss of surface area 9410 ± 91.6 µm2. The air abrasion unit was shown to have the least detrimental effect on the implant surface when removing the artificial dental calculus compared to the other three methods. © The Author(s) 2024.
  • No Thumbnail Available
    Item
    High-Temperature Sliding Wear Characterization Studies of AISI 316 L(N) by Surface Profilometry
    (Springer Science and Business Media Deutschland GmbH, 2020) Aruldev, N.; Parthasarathi, N.L.; Rajasekaran, B.; Borah, U.
    The major construction material in the Prototype Fast Breeder Reactor (PFBR) is AISI-type 316 L(N) austenitic stainless steel due to its good mechanical properties and compatibility with liquid sodium.Sliding wear experiments were carried out at various temperatures up to 550 ℃ at constant load (20 N) and sliding speed (0.8 m/s) using a pin-on-disc test rig as per the ASTM standard G99-05. Analysis of the test results presented that the wear increased considerably with the temperature. The characterization of worn surface topography is done by a complete profilometry study using Talysurf CLI 1000 surface profilometer. The 3D surfaces were captured both by induction mode by diamond stylus as well as non-contact high-resolution confocal point gauge having range of 3000 μm with 0.25 nm resolution was used for surface profiling. The cold-welded surfaces were analysed by the profilometer, and the geometry of the deposit on the wear track was analysed by the profilometer. The roughness parameters were correlated with the amount of wear data obtained from the experiments at various testing temperatures. As the temperature increases during the sliding wear, the material loss is presented with more furrows resulting in enhanced surface roughness values. © 2020, Springer Nature Singapore Pte Ltd.
  • No Thumbnail Available
    Item
    Sliding wear behaviour of Ni-5 %Al coating deposited by detonation spray on IN718
    (Elsevier Ltd, 2022) Purushotham, N.; Rajasekaran, B.; Parthasarathi, N.L.; Praveen, K.; Govindarajan, G.
    Ni-5 %Al metallic coating was deposited on Nickel-based superalloy (IN718) specimens using the detonation spray coating (DSC) method. Detonation spraying yielded coating with extreme chemical bond strength, hardness, and less porosity. The microstructure, microhardness, and room temperature pin-on-disc sliding wear behavior of the Ni-5 %Al coating and the as-received IN718 superalloy were evaluated. Sliding wear tests were done at room temperature (25 °C), under different loading conditions (6 N and 10 N), using an alumina (Al2O3) ball-on-disk tribometer and friction coefficients were measured. The study of worn surfaces conducted by SEM indicated that both Ni-5 %Al coating and the substrate suffered significant abrasive wear with occasional adhesion and spalling of the coating. The 3D topography of the wear track was examined by a 3D non-contact profilometer, which enabled the quantification of the wear. The friction coefficient values of the tests and the wear in terms of mass loss were in good correlation. © 2022