Characterization of wear resistance of thermally sprayed coatings. Emilie Gagliardo Florian Haussoulliez

Transcription

1 Characterization of wear resistance of thermally sprayed coatings Emilie Gagliardo Florian Haussoulliez

2 Introduction I) Presentation of the Institute of Plasma Physics II) Processes III) Experimental method (SAR test) IV) Studied coatings and Results Conclusion

3 Introduction Coatings improve the surface properties of the substrate Samples provided by Skoda and Bodycote (Ambazac) companies Coatings realized by HVOF, Plasma spraying and WSP Use of the Slurry Abrasion Response test of IPP according to the ASTM G75, roughness and hardness measurements Studied coatings: Carbides, Cobalt-based alloys, Nickel-Chromium alloys and Al 2 O 3 /TiO 2 ceramics aim: determine the wear resistance of samples and explain it

4 I) Presentation of the Institute of Plasma Physics Originally known as the Institute of Vacuum Electronics of the Czechoslovak Academy of Sciences, the Institute of Plasma Physics was founded on January 1, 1959 specialized in corona discharges in water, thermal plasma generation in a water stabilized torch, high temperature plasma, laser plasma and plasma deposited materials numerous patents in several developed countries many collaborating institutions six research departments Materials Engineering: the study of properties of plasma deposited materials

5 II) Processes Plasma spraying Fig 1: Plasma Spraying Process with a gas-stabilized torch produces a high quality coating by a combination of a high temperature and high energy heat source oxidation of the sprayed material may occur vacuum plasma (VPS) or low pressure plasma spraying (LPPS)

6 Deposit properties: Sizes of feedstock powders: from micrometers to about 100 micrometers The lamellae have thickness in the micrometer range and lateral dimension from several to hundreds of micrometers The void ratio varies from less than 1% to 10% Fig.2: Schematic Diagram of Thermal Spray Metal Coating

7 HVOF Fig 3: High Velocity Oxy Fuel Process Advantages: - create a dense, durable coating, less than 1% porosity, high adhesion - used to produce very wear resistant coatings such as cermets Drawbacks: - noisy - a level of 150 db is reached - the oxidation of particles in flight - low temperature which limits the processing adaptability for ceramics, and mainly high melting point materials

8 WSP (Water-stabilized plasma) II) Processes Fig.4: Scheme of WSP spraying: 1 cathode (consumable graphite rod), 2 cooling water for cathode, 3 water inlet for stabilizing channel, 4 water outlet, 5 powder feeding tubes, 6 anode shift, 7 anode rotation, 8 water vortex, 9 electric arc, 10 - coating, 11 substrate, FD feeding distance, SD spray distance.

9 III) Experimental method : SAR (Slurry Abrasion Response test) Fig.15: Scheme of the wear-test machine (1) rotating wheel, (2) switch and round meter, (3) direct drive, (4) dead weight, (5) sample holder, (6) slurry, (7) neoprene lap, (8) sample, (9) specimen lifting cam slurry: 150g of Alumina powder and 150g of water Rubber A590 Load: 22.2N

10 The wear rate is expressed in cubic millimetres of the sample surface per meter [mm 3 /m]. We must know the density. The inverse wear rate is used [m/mm 3 ]. It shows how many meters in the slurry are necessary to pass to wear out one cubic mm of the coating material. The parameter k can be expressed in g/m 3 and describes the slope of the line tangent to the curve which represents the weight losses (or volume losses).

11 Characterization of Alumina powder Powder morphology: Fig.19: Alumina powder AB240 before the test - particle size between 30 and 60 µm - the density is 3.9 g/cm 3

12 Volume loss as a function of the sliding distance for Bodycote samples

13 IV) Studied coatings and Results Carbides WC10Co4Cr, WC-20CrC-7Ni: hardness close to diamond WC particles form the major wear-resistant constituent Co binder provides toughness and cohesion Microstructural features of WC10Co4Cr (density = 13.9 g/cm 3 ) Cr 3 C 2-35NiCr, Cr 2 C 3 -NiCr, Cr 3 C 2-25%CoCrNiAlY: excellent oxidation resistance higher coating brittleness than WC-Co wear resistance lower than WC coating Microstructural features of Cr 3 C 2-35NiCr (density = 6.6 g/cm 3 )

14 Wear test on carbides coatings sample inverse wear rate (m/mm 3 ) k (g/m 3 ) hardness HV 0.3 Ry max ave_b (µm) R a ave_b (µm) R a ave-b R a ave-a (µm) WC10Co4Cr (HVOF NG) WC10Co4Cr (HP- HVOF) WC-20%CrC- 7%Ni (Réf. 116) Cr 3 C 2-25%CoCrNiAlY (Réf. 111) Cr 2 C 3 -NiCr (HP- HVOF) Cr 3 C 2-35%NiCr (Réf. 74) green color: Skoda samples (Skoda HVOF WC-17Co 2007, i.w.r. 2252) white color: Bodycote samples

15 Inverse wear rate for Carbides coatings 3500 inverse wear rate m/mm WC10Co4Cr (HVOF NG) WC10Co4Cr (HP-HVOF) WC-20%CrC- 7%Ni (Réf. 116) Cr3C2-25%CoCrNiAlY (Réf. 111) Cr2C3-NiCr (HP-HVOF) Cr3C2-35%NiCr (Réf. 74) sample WC-based materials exhibit the best wear resistance at conditions of the SAR test HVOF NG: deposition rates of powder higher than the HP-HVOF process best results

16 Scheme of WC particles removal contact of WC particles with Co is not so good and during the slurry test, WC particles are worn and removed Ra after the test > Ra before the test

17 NiCrMoWFe (Hastelloy C276): NiCrAlY: Nickel-chromium alloys excellent corrosion resistance but a relatively poor wear-resistance high temperature oxidation resistance NiCrBSi: Microstructural features of NiCrMoWFe (density = 8.14 g/cm 3 ) provides a high wear and corrosion resistance at high temperatures applied in the form of thick protective coatings Microstructural features of NiCrBSi (density = 7.12 g/cm 3 ) Inconel 718: good corrosion and high mechanical properties used for heat treatment recipients

18 Wear test on Nickel-chromium alloy coatings sample inverse wear rate (m/mm 3 ) k (g/m 3 ) hardness HV 0.3 Ry max ave_b (µm) R a ave_b (µm) R a ave-b R a ave-a (µm) NiCrBSi (HVOF NG) NiCrAlY (Plasma) NiCrMoWFe (Réf. 86) Inconel 718 (Réf.80) roughness is quite high more the roughness is high, more the sample wears green color: Bodycote samples white color: Skoda samples

19 Inverse wear rate for Nickel Chromium alloy inverse wear rate m/mm NiCrBSi (HVOF NG) NiCrAlY (Plasma) NiCrMoWFe (Réf. 86) Inconel (Réf.80) sam ple These coatings have a wear resistance lower than Carbides coatings NiCrBSi is the most interesting coating for wear resistance applications

20 Cobalt and cobalt base alloys CoMoCrSi (Laves-phase-containing alloys) alloying elements Mo and Si: formation of a hard and corrosion resistant structure known as Laves phase contain vol.% of Laves phase wear resistance of these alloys dependent on the volume percentage of Laves phase Microstructural features of CoMoCrSi (density = 8.44 g/cm 3 ) Stellite Grade 6 (Carbide-containing cobalt-based alloys) the most widely used of the wear resistant cobalt based alloys Microstructural features of Stellite Grade 6 (density = 8.44 g/cm 3 ) the carbide content controls the hardness and the level of abrasion resistance

21 Wear test on Cobalt and cobalt-based alloy coatings sample inverse wear rate (m/mm 3 ) k (g/m 3 ) hardness HV 0.3 Ry max ave_b (µm) R a ave_b (µm) R a ave-b R a ave-a (µm) Stellite Grade 6 (Plasma) Stellite Grade 6 (HP-HVOF) CoMoCrSi (Réf. 105) Similar results for Stellite grade 6 sprayed by plasma or HP-HVOF Stellite has the best wear resistance: contains Carbides CoMoCrSi has maybe a low Laves phase content here green color: Skoda samples white color: Bodycote samples

22 Inverse wear rate for Cobalt and Cobalt-based alloy 70 inverse wear rate m/mm Stellite Grade 6 (Plasm a) Stellite Grade 6 (HP-HVOF) sample CoMoCrSi (Réf. 105) Stellite Grade 6 is the most interesting coating for wear resistance applications

23 Al 2 O 3 /TiO 2 ceramic coatings dense and hard surface coating α-al 2 O 3, which is the most desirable phase depending on the application, different TiO 2 weight percentages are added to pure Al 2 O 3 such as 3%, 13% and 40% weight content 60% of Al 2 O 3 and 40% of TiO 2 in our case

24 Alumina-Titania coating results Sprayed by WSP sample inverse wear rate m/mm 3 wear rate mm 3 /m Wear coef. [mm 3 /Nm] AT ,5252E-04 comprised of interlamellar porosity, cracks and unmelted particles the porosity equal to 11.5% 210.2m/mm 3 for pure alumina and 30.9m/mm 3 for pure titania with nanometric agglomerated powder

25 Microstructural features of AT40 cross-section Unmelted particle lamellar coating structure Microstructural features of pure Alumina crosssection Microstructural features of pure Titania crosssection

26 Microhardness of AT-coatings

27 Conclusion Tungsten Carbides have the best wear resistance The HVOF NG process provides the best result promising process The difference in roughness before the test and after the test is in relation to the wear resistance NiCrBSi is the most interesting coating for wear resistance applications among the Nickel-chromium alloy coatings Stellite Grade 6 is the most interesting coating for wear resistance applications among the cobalt-based alloy coatings Al 2 O 3-40%TiO 2 exhibits better microhardness and inverse wear rate than other coatings with lower content of TiO 2

28 References Standard test method for determination of slurry abrasivity (Miller number) and slurry abrasion response of materials (SAR number), Tech. Rep. ASTM G75-95, ASTM, Philadelphia, Pa, USA, 2002 V. Brožek, P. Ctibor, D. I. Cheong, S.-H. Yang, Plasma Spraying of Zirconium Carbide- Hafnium Carbide- Tungsten Cermets, Powder Metallurgy Progress, Vol.9 (2009), No 1 Irina Hussainova, Juri Pirso, Maksim Antonov, Kristjan Juhani and Sergei Letunovitš, Erosion and abrasion of chromium carbide based cermets produced by different methods, 16th International Conference on Wear of Materials, Volume 263, Issues 7-12, 10 September 2007, Pages A. Davidescu, G. G. Savii, C. Sticlaru, Analysis of HVOF-sprayed MCrAlY coatings using SEM image processing, Journal of Optoelectronics and Advanced Materials, 7 (6), pp , 2005 Anupama Sahu, Rojaleena Das, S. Sen, S.C.Mishra, Alok Satapathy, P.V.Ananthapadmanabhan and K.P.Sreekumar, Al2O3-TiO2 Wear Resistant Coatings: A Neural Computation, International Conference on Advanced Materials and Composites (ICAMC-2007), NIIST, Trivandrum, Oct 24-26, 2007, p Nuchjira Dejang, Supranee Pitsamai, Sittichai Wirojanupatump and Sukanda jansirisonboon, Microstructure and Phase Analyses of Flame-Sprayed Al2O3-40wt%TiO2 Coating, Thailand Materials Science and Technology Conference 4th, MSAT-CP-33, 2006

29 Thank you for your attention