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Slurry erosion comparison of d gun sprayed stellite-6, cr3 c2-25nicr coatings-2

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  • 1. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME210SLURRY EROSION COMPARISON OF D-GUN SPRAYED STELLITE-6, Cr3C2-25NiCr COATINGS AND SUBSTRATE 13Cr4Ni UNDERHYDRO ACCELERATED CONDITIONGurpreet Singh1and Sanjeev Bhandari21M.Tech, Department of Mechanical Engineering,Baba Banda Singh Bahadur Engineering College, Fatehgarh Sahib, Punjab-140407, India2Assistant Professor, Department of Mechanical Engineering,Baba Banda Singh Bahadur Engineering College, Fatehgarh Sahib, Punjab-140407, IndiaABSTRACTDegradation of under water parts in hydro turbines is serious issue mainly in theNorth India. So it’s a challenge to develop new more erosion resistant materials. In thepresent study, slurry erosion performance of detonation gun (D-gun) spray ceramic coatings(Stellite-6 and Cr3C2-25NiCr) on 13Cr4Ni stainless steel has been investigated. Attempt hasbeen made to study the comparison between coatings and substrate steel under a particular setof parameters (concentration, average particle size and rotational speed) in hydro acceleratedcondition. Commercially available silica sand is used as an abrasive media. Allexperimentation is done in High Speed Erosion Test rig. Comparison is made on twodifferent angles i.e. 30° and 90°. At 30°, Stellite-6 coating performed better in comparisonwith Cr3C2-25NiCr coating and substrate steel specimen. On the other hand substrate steelspecimen performed better at 90° than the coatings.Index Terms - Slurry erosion, High speed erosion tester, D-gun Spraying, Ceramic coatings.1. INTRODUCTIONHydro power plants which are located on the Himalayan Rivers have had to facehigh silt content in the water passing through the turbines causing the large amount ofdamage to various under water components of turbines like runner, guide vanes, needles andseats of Pelton-type turbines. Water contains Quartz, Tourmaline, Garnet, Zircon, etc ofHardness 7 on mho scale [1]. These sediments are formed due to the fragmentation of rocks,erosion of land and land sliding because of heavy rains during the monsoon period in theINTERNATIONAL JOURNAL OF ADVANCED RESEARCH INENGINEERING AND TECHNOLOGY (IJARET)ISSN 0976 - 6480 (Print)ISSN 0976 - 6499 (Online)Volume 4, Issue 2 March – April 2013, pp. 210-222© IAEME: www.iaeme.com/ijaret.aspJournal Impact Factor (2013): 5.8376 (Calculated by GISI)www.jifactor.comIJARET© I A E M E
  • 2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME211Himalayan region of India [2]. Because of this kind of environment erosion of turbinecomponents occurs [3]. Erosion due to the impact of hard particles is common phenomenonof underwater parts in turbines [4]. A lot of investigations have been done by the researchersto identify the factors responsible for the slurry erosion behavior of turbine materials due tothe water containing silt. It has been shown that slurry erosion at oblique angle can generate arougher surface when compared with that at normal incident. Also at oblique angles it canrender a greater susceptibility to pitting during erosion than at normal incident. ThusIndividual erosion events at oblique angles are thus expected to be more destructive thanthose at normal incident [5]. Ductile materials during erosion are considered to loose materialthrough a cutting and ploughing mechanism at a low impact angle [6]. On the other hand,cracking, fragmentation and removal of flakes is common phenomenon of erosion in brittlematerials [7].1.1 Detonation Spray CoatingTo improve the surface performance and durability of engineering componentswhich expose to different forms of wear such as abrasion, erosion and corrosion ThermalSpray techniques are a versatile means of developing a large variety of coatings/protectivelayers [8–10]. Detonation gun (D-gun) spray process is a thermal spray coating process,which provides an extremely low porosity, good adhesive strength, coating surface withcompressive residual stresses, low oxide contents and high intersplat strength [11, 12]. TheD-gun spray process involves the impingement of powdered materials with the supersonicspeed through a water-cooled barrel on the surface of substrate. The two phase mixture ofcoating are heated to plasticity and impinges against a target substrate, where the hightemperature, high velocity coating particles bond into the surface of substrate and amechanical interlocking and microscopic welding may take place [13]. Ceramic materials arenow commonly employed in the form of coatings to resist wear. Due to high melting point ofthe ceramic powders which require a high temperature jet to get deformed during coatingformation, these coatings are usually deposited by atmospheric plasma spraying [14].However, plasma sprayed coatings are possess more porous and brittle nature than highvelocity thermal-sprayed coatings [15, 16]. On the other hand, due to close interlamellarcontacts and small porosity, the high-velocity combustion spraying techniques providesgreater hardness [17, 18]. This is why several efforts have been undertaken to use these high-velocity spray techniques like to spray oxides D-gun spraying is mainly used [18].2. EXPERIMENTATION2.1 MaterialCA6NM steel containing 13% Cr and 4% Ni (also known as 13/4) is being used infabrication of hydro turbine underwater parts. Chemical composition of 13/4 stainless steel isgiven in table 1. Rectangular specimens of 10 mm x 10 mm were prepared.Table 1. Chemical composition of 13/4 stainless steel (wt %)Steel C Si Mn Cr Ni N S Cu Co P Mo Fe13/4 0.06 0.74 1.16 13.14 3.9 -- 0.014 0.088 0.035 0.015 0.61 Bal.
  • 3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME2122.1 Deposition of CoatingsCommercially available powder of Stellite-6 and Cr3C2-25NiCr are coated on13Cr4Ni stainless steel using D-Gun process available with SVX Powder M SurfaceEngineering Pvt. Ltd., Noida, India.2.2 Slurry Erosion TestingA high speed erosion tester (DUCOM TR401, Bangalore make) was used to studythe slurry erosion behavior of 13Cr4Ni stainless steel specimens. The tester shown in Figure1 consists of various components such as slurry abrasion chamber, slurry tank, rotor, controlpanel, 3 phase induction motor.Figure 1 Experimental setup of High Speed Erosion Tester (DUCOM TR401)In slurry abrasion chamber test specimens and slurry is enclosed and specimens arerotated. Slurry tank is a cylindrical vessel made up of stainless steel, in which the slurry isprepared to the required concentration. There are three inlet and three outlet pipes betweenslurry abrasion chamber and slurry tank for re-circulation of slurry. Due to rotation of rotorvacuum is created in the slurry abrasion chamber and therefore slurry from cylindrical vesselthrough inlet pipes to chamber and used slurry leaves the chamber and enters the tank frombottom side through outlet pipes, thus ensuring continuous re-circulation of slurry. This highspeed erosion tester is capable of creating accelerated hydro conditions to simulate theerosion of standard test specimens with water containing abrasive particles of controlled sizeand composition (slurry). Main advantages of this rig is that at a time, 12 specimens may betested, thus ensuring zero tolerance to change of experimental conditions during comparisonof slurry erosion testing of different specimens under similar experimental conditions. Onlycylindrical samples can be tested in this tester.
  • 4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME213For placing rectangular specimen in this tester we needed to design a specimenholder in which we can accommodate rectangular specimen. After two different designs wedesign the specimen holder shown in Fig 2.Figure 2 Specimen holders for rectangular specimensT 304 Stainless Steel Square bar was selected for the fabrication of specimen holdersas it is ideal for all applications where greater strength and superior corrosion resistance isrequired. 304 Stainless Square has a durable dull, mill finish that is widely used for all typesof fabrication projects that are exposed to the elements - chemical, acidic, fresh water, andsalt water environments. Specifications, application and Mechanical Properties of T304stainless steel are mention in table 2.Table 2 Specifications, application and Mechanical Properties of T304 stainless steelSpecifications of T304 ASTM A276, QQS-763, T304/304L, non-polished finish.Applications Frame work, braces, supports, shafts, axels, marine, etc.Workability Easy to Weld, Moderate Cutting, Forming and Machining.Mechanical Properties Brinell = 170,Tensile Strength = 505 MPa,Yield Strength = 215 MPa,NonmagneticEffect of average particle size, concentration (ppm) and velocity has been studied byseveral researchers and showed that these are significant factors, which can affect the erosionphenomenon. To study this, commercially used silica sand is used as slurry medium as silicais found to be main constituent of slurry as is evident from the literature; the slurry is found tobe consisting of SiO2, Al2O3, CaO, and MgO in hydro power plant in northern India [4,19].Slurry concentrations having average particle sizes of 300 µm were prepared tosimulate the test in more accelerated conditions. Tests were carried under concentration of10000 ppm, with erodent particle size 300 µm and rotation speed of 3800 rpm to study theslurry erosion performance of Stellite-6 and Cr3C2-25NiCr coated 13Cr4Ni and 13Cr4Nistainless steel which were placed at 2 different angles i.e 30° and 90°. These two angles were
  • 5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME214select to analyze the performance of specimen when sand particles strike the surfacetangentially and normally.The interaction of slurry particles with rectangular specimen in slurry chamber isshown in Figure 3. A typical erosion test cycle began with mounting of specimen holder atthe proper place at correct angle. Then specimen was placed in the holders in the slurrychamber. After fixing the specimens in holders every time chamber was made air tight bytightening the nuts at four places so that proper vacuum can be created. The water was filledin stainless steel water tank and silica sand of appropriate particle size was added to the waterfor preparing required concentration. Then rotational speed was set and test was started. Aftercompleting the slurry erosion testing cycle of 1 h, specimens were removed from the rotorassembly, brushed gently and cleaned with acetone to remove attached sand particles if any.The specimens were weighed before and after each slurry erosion cycle. The loss in mass ofeach specimen was recorded with the help of precision micro weighing scale having anaccuracy of 0.1 mg. As erosion is a surface phenomenon so the peripheral surface area ofeach specimen was calculated by measuring the length and width at two places, taking theirmean for getting average length and width of specimen with the help of digital vernier caliperof least count 0.01 mm.Figure 3 Interaction of slurry particles with rectangular specimen in slurry chamber
  • 6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME215Specific mass loss was calculated usingSpecific mass loss = mass loss (g) X 106/ Exposed surface area (m2)The slurry erosion process was repeated for six cycles for each of the samples Theresults have been plotted as cumulative mass loss per unit area in (g/m2) versus time ofexposure (h) to ascertain the kinetics of slurry erosion behavior of coatings and substrate.3. RESULTS AND DISCUSSIONFigure 4 shows cumulative weight loss per unit area (g/m2) versus time (h) graph ofbared 13Cr4Ni stainless steel and Stellite-6 coated 13Cr4Ni at 30° under a set of parametersof concentration of 10000 ppm, erodent particle size 300 µ and rotation speed of 3800 rpm.From graph it can be observed that as the time increases the cumulative weight loss per unitarea increases for both materials. Also it can be seen that after a run of 6 hours overallspecific weight loss for 13Cr4Ni is 1897.43 g/m2and for Stellite-6 coating it is 345.31 g/m2.It means specific weight loss for 13Cr4Ni is 5.5 times the specific weight loss of Stellite-6.Figure 4 Comparision between cumulative mass loss per unit area of 13Cr4Ni and Stellite-6at 30°Figure 5 shows cumulative weight loss per unit area (g/m2) versus time (h) graph ofbared 13Cr4Ni stainless steel and Stellite-6 coated 13Cr4Ni at 90° under same set ofparameters. It can be observed that as time progresses cumulative weight loss per unit areaalso increases. After a run of 6 hours overall specific weight loss for 13Cr4Ni is 172.87 g/m2and for Stellite-6 coating it is 420.82 g/m2. It means specific weight loss for Stellite-6 is 2.43times the 13Cr4Ni.
  • 7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME216In Figure 6 there is a comparison between 13Cr4Ni and Cr3C2-25NiCr at 30° oncumulative mass loss per unit area versus time graph. With the increase in time weight lossper unit area increases for both. After 6 hour run overall specific weight loss for 13Cr4Ni is1897.43 g/m2and for Stellite-6 coating it is 1399.19 g/m2. Specific weight loss for 13Cr4Ni is1.35 times specific weight loss for Stellite-6.Figure 5 Comparision between cumulative mass loss per unit area of 13Cr4Ni and Stellite-6at 90°Figure 6 Comparision between cumulative mass loss per unit area of 13Cr4Ni and Cr3C2-25NiCr at 30°
  • 8. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME217The cumulative specific mass loss curves of the 13Cr4Ni and Cr3C2-25NiCr coated13Cr4Ni steel at 90° for a total duration of 6-h slurry erosion testing are shown in Figure 7for same set of parameters. It can be observed from the graph that the overall specific masslosses are remarkably different. The maximum specific weight loss at the end of 6 hour ofslurry erosion testing for the bared 13Cr4Ni and Cr3C2-25NiCr coating is 968.57 and 172.87g/m2, respectively. So it can be observed coating is eroded 5.6 times than bared steel.Figure 7 Comparision between cumulative mass loss per unit area of 13Cr4Ni and Cr3C2-25NiCr at 90°Figure 8 depicts the comparision chart between cumulative mass loss per unit area ofStellite-6 and Cr3C2-25NiCr at 30° and in Figure 9 Stellite-6 and Cr3C2-25NiCr at 90 ° for atotal duration of 6-h slurry erosion testing with same set of parametes. At 30° the maximumspecific mass loss at the end of 6 hour run is 345.31 and 1399.19 g/m2for Stellite-6 andCr3C2-25NiCr respectively. At 90° the maximum specific mass loss at the end of 6 hour runis 420.82 and 968.57 g/m2for Stellite-6 and Cr3C2-25NiCr respectively. It can be observedthat from Figure 8 and 9 that maximum specific weight loss for Stellite-6 is less than that ofCr3C2-25NiCr. Maximum specific weight loss after 6 hour for Cr3C2-25NiCr is 4.05 timesthan Stellite-6 at 30° while at 90° maximum specific weight loss for Cr3C2-25NiCr is 2.3times than Stellite-6.
  • 9. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME218Figure 8 Comparision between cumulative mass loss per unit area of Stellite-6 and Cr3C2-25NiCr at 30°Figure 9 Comparision between cumulative mass loss per unit area of Stellite-6 and Cr3C2-25NiCr at 90°
  • 10. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME219Figure 10 shows cumulative weight loss per unit area (g/m2) versus time (h) graph ofbared 13Cr4Ni stainless steel 30° and 90° under same set of parameters. It can be seen fromthe graph that that 13Cr4Ni get more eroded at 30° than at 90° approximately 11 times. Asthe maximum weight loss for 13Cr4Ni at 30° is 1897.43 g/m2and at 90° it is 172.87 g/m2after 6 hour run in erosion tester.Figure 10 Comparision between cumulative mass loss per unit area of 13Cr4Ni at 30° and90°Cumulative mass loss per unit area of Stellite-6 at 30° and 90° is shown in Figure 11.From the graph it can be seen that Stellite-6 performed better at 30° as the maximum weightloss for Stellite-6 at 30° is less than the Stellite-6 at 90°. The maximum weight loss forStellite-6 at 30° is 345.31 g/m2and at 90° it is 420.82 g/m2.In Figure 12 there is a comparison between cumulative mass loss per unit area ofCr3C2-25NiCr at 30° and 90°. More erosion of Cr3C2-25NiCr takes place at 30°. Themaximum weight loss for Cr3C2-25NiCr is 1399.19 and 968.57 g/m2at 30° and 90°respectively after a 6 hour run in slury erosion chamber of high speed tester. The ratio ofmaximum weight loss at 30° to 90° comes out 1.44.
  • 11. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME220Figure 11 Comparision between cumulative mass loss per unit area of Stellite-6 at 30° and90°Figure 12 Comparision between cumulative mass loss per unit area of Cr3C2-25NiCr at 30°and 90°
  • 12. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME2214. CONCLUSIONSDue to higher hardness, Stellite-6 coating performed better at 30° than uncoated13Cr4Ni while substrate13Cr4Ni steel (due to high toughness) showed better slurryresistance than Stellite-6 coating at 90°.Cr3C2-25NiCr coating was found to be more erosion resistant at 30° than bared13Cr4Ni but not at 90°. At 90° substrate 13Cr4Ni steel showed far much betterperforamnce than Cr3C2-25NiCr coating.While comparing both coatings it was found that Stellite-6 coating ( due to highertoughness) is more resistant to slurry erosion than Cr3C2-25NiCr coating at 30° aswell as at 90°.Uncoated 13Cr4Ni steel and Cr3C2-25NiCr coating showed a better performance toslurry erosion at 90° than at 30° while Stelite-6 coating was better at 90° whencompraing their performances separately at two different angles.5. REFERENCES1. R.P.Singh, “Silt damage control measures for underwater parts-Nathpa Jhakri HydroPower Station,” Case study of a success story, Vol. 66, No. 1, January-March, 2009, p.36-42.2. B.S.K. Naidu, “Renovation and Modernization of Silt Prone Hydropower Stations inIndia,” Workshop on Silting Problems in Hydroelectric Power Stations, June 25-26,1987 (New Delhi), p V-13-V-16.3. B.S. Mann, High-Energy Particle Impact Wear Resistance of Hard Coatings and TheirApplication in Hydro Turbines, Wear, 2000, 237, p 140-146.4. A. K. Chauhan, D. B. Goel and S. Prakash, “Erosion behaviour of hydro turbine steels,”Bull. Material Science, Vol. 31, No. 2, April 2008, pp. 115–120.5. G.T. Burstein, K. Sasaki, “Effect of impact angle on the slurry erosion–corrosion of304L stainless steel,” Wear, 2000, 240, p. 80-94.6. G.I. Sheldon, A. Kanhere, “An investigation of impingement erosion using singleparticles,” Wear 21, 1972, p. 195–209.7. I. Finnie, “Erosion of surfaces by solid particles,” Wear 3, 1960, p. 87–103.8. S.V. Joshi, R. Sivakumar, “Protective coatings by plasma spraying,” Trans. IndianCeram. Soc. 50, 1999, p. 50–59.9. K.G. Budinski, “Surface engineering for wear resistance,” Prentice Hall, EnglewoodCliffs, 1988.10. F. Rastegar, D.E. Richardson, “Alternative to chrome: HVOF cermet coatings for highhorse power diesel engines,” Surf. Coat. Technol. 90, 1997, p. 156–193.11. B. Rajasekaran, S.G.S. Raman, S. Joshi, G. Sundararajan, “Influence of detonation gunsprayed alumina coating on AA 6063 samples under cyclic loading with and withoutfretting,” Tribol. Int. 41(4), 2008, p. 315–322.12. P.M.J. Vuoristo, K. Niemi, T. Mantyala, “On the properties of detonation gun sprayedand plasma sprayed ceramic coatings,” Berndt, C. (ed.) Thermal Spray: InternationalAdvances in Coatings Technology, pp. 171–175. ASM International, Metals Park, OH,1992.13. W. Wolentarski, “Material coating by the Detonation Gun process,” Proceedings of theeleventh turbomachinery symposium, Newyork.
  • 13. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME22214. Y. Liu, T.E. Fischer, A. Dent, “Comparison of HVOF and plasma-sprayed alumina/titania coatings—microstructure, mechanical properties and abrasion behavior,” Surf.Coat. Technol. 167, 2003, p. 68–76.15. P.P. Psyllaki, M. Jeandin, D.I. Pantelis, “Microstructure and wear mechanisms ofthermal-sprayed alumina,” Coat. Mater. Lett. 47, 2001, p. 77–82.16. J. Voyer, B.R. Marple, “Sliding wear behavior of high velocity oxy-fuel and high powerplasma spray-processed tungsten carbide- based cermet coatings,” Wear 225–229,1999, p. 135–145.17. Y. Wang, “Friction and wear performances of detonation-gun and plasma-sprayedceramic and cermet hard coatings under dry friction,” Wear 161, 1993, p. 69–78.18. L. Pawlowski, “The Science and Engineering of Thermal Spray Coatings,” Wiley, WestSusseex P109 IUD, 1995.19. S. Bhandari, H. Singh, H. K. Kansal, V. Rastogi, “Slurry Erosion Behaviour ofDetonation Gun Spray Al2O3 and Al2O3–13TiO2-Coated CF8M Steel Under HydroAccelerated Conditions,” Tribol Lett 45, 2012, p. 319–331.20. Prof. Mohammed Yunus, Dr. J. Fazlur Rahman and S.Ferozkhan, “A GeneticProgramming Approach for the Prediction of Thermal Characteristics of CeramicCoatings”, International Journal of Industrial Engineering Research and Development(IJIERD), Volume 2, Issue 1, 2011, pp. 69 - 79, ISSN Online: 0976 - 6979, ISSN Print:0976 – 6987.21. Mohammed Yunus, Dr. J. Fazlur Rahman and S.Ferozkhan, “Prediction of Mechanicaland Tribological Characteristics of Industrial Ceramic Coatings using a GeneticProgramming Approach”, International Journal of Mechanical Engineering &Technology (IJMET), Volume 3, Issue 1, 2012, pp. 77 - 89, ISSN Print: 0976 – 6340,ISSN Online: 0976 – 6359.22. Mohammed Yunus, Dr. J. Fazlur Rahman and S.Ferozkhan, “Evaluation ofMachinability Characteristics of Industrial Ceramic Coatings using GeneticProgramming Based Approach”, International Journal of Mechanical Engineering &Technology (IJMET), Volume 2, Issue 2, 2011, pp. 126 - 137, ISSN Print: 0976 – 6340,ISSN Online: 0976 – 6359.