Earlier positions, e.g.:
Senior Scientist at VTT Technical Research Centre of Finland;
Visiting scholar, University of California at Berkeley, USA;
Senior research fellow, Department of Materials Science, Tampere University of Technology, Finland;
Academy research fellow, the Academy of Finland;
Post-doctoral researcher, Corrosion and Protection Centre, The University of Manchester, UK.
Professor of Surface Engineering in Tampere University, research group leader
Our research group does what were are always been interested in: scientific and applied research in order to understand the processing/structure/properties/performance relationships of advanced coatings and surface treatments.
The main research interests involve preparation of novel coatings and surface treatments by using various thermal spray deposition technologies, including plasma spraying, high-velocity oxygen/air fuel spraying (HVOF, HVAF), cold spraying, electric arc spraying, powder and wire flame spraying, suspension and solution spraying technologies, by high power laser and weld surfacing, and by magnetron sputtering. Characterization of microstructure and engineering and functional properties of novel coatings and surface treatments. Performance of coatings in selected industrial applications, including mechanical engineering, power generation, pulp and paper manufacturing, corrosion and wear protection, tribology, and several other industrial uses of coatings.
Surface Engineering Research Group, Thermal Spray Center Finland (TSCF)
Surface engineering, materials engineering
Professor of Surface Engineering, Tampere University of Technology, from 2002 to present
Senior Researcher, Tampere University of Technology, 1995-2002
Special Researcher, Tampere University of Technology, 1989-1995
Researcher, Tampere University of Technology, 1982-1989
Dr. Tech. 1992, Tampere University of Technology
Lic. Tech. 1987, Tampere University of Technology
M.Sc. (Eng.) 1981, Tampere University of Technology
ASM Thermal Spray Hall of Fame (ASM TSS HoF, 2017), American Society of Materials International, “For long term contributions for the advancement of thermal spray and related deposition technologies through worldwide education and practice.”
Fellow of American Society of Materials International (FASM, 2015), “For continuous and dedicated contributions towards the advancement of thermal spray, cold spray, and laser cladding technologies worldwide through education and practice”.
My research interests are in scientific and applied research in order to understand and control the processing/structure/properties/performance relationships of advanced coatings and surface treatments, with a special focus in thermal spraying, laser and weld surfacing, and thin film technologies.
T. Varis, T. Suhonen, J. Laakso, M. Jokipii, P. Vuoristo: Evaluation of Residual Stresses and Their Influence on Cavitation Erosion Resistance of High Kinetic HVOF and HVAF-Sprayed WC-CoCr Coatings. Journal of Thermal Spray Technology, 2020, https://doi.org/10.1007/s11666-020-01037-2.
G. Bolelli, D. Meschini, T. Varis, V. Testa, S. Morelli, L. Lusvarghi, P. Vuoristo: Corrosion Properties of Thermally Sprayed Bond Coatings Under Plasma-Sprayed Chromia Coating in Sulfuric Acid Solutions. Journal of Thermal Spray Technology volume 29, pages270–284(2020).
M. Karhu, J. Lagerbom, M. Honkanen, E. Huttunen-Saarivirta, J. Kiilakoski, P. Vuoristo, S. Solismaa, P. Kivikytö-Reponen: Mining tailings as a raw material for glass-bonded thermally sprayed ceramic coatings: Microstructure and properties. Journal of the European Ceramic Society, May 2020.
V. Donadei, H. Koivuluoto, E. Sarlin, P. Vuoristo: Icephobic Behaviour and Thermal Stability of Flame-Sprayed Polyethylene Coating: The Effect of Process Parameters. Journal of Thermal Spray Technology 29 (1-2), 241-254.
J. Kiilakoski, R. Trache, S. Björklund, S. Joshi, P. Vuoristo: Process Parameter Impact on Suspension-HVOF-Sprayed Cr2O3 Coatings. Journal of Thermal Spray Technology 28 (8), 1933-1944.
D. Fantozzi, V. Matikainen, M. Uusitalo, H. Koivuluoto, P. Vuoristo: Chlorine induced high-temperature corrosion mechanisms in HVOF and HVAF sprayed Cr3C2-based hardmetal coatings. Corrosion Science 160, 108166.
P. Vuoristo: Thermal spray coating processes, book chapter in Comprehensive materials processing, 1st edition, Volume 4: Coatings and films. Cameron, D. (ed.). Elsevier, p. 229-276, 2014.
J. Tuominen, M. Kaubisch, S. Thieme, J. Näkki, S. Nowotny, P. Vuoristo: Laser strip cladding for large area metal deposition. Additive Manufacturing 27, 208-216.
V. Matikainen, G. Bolelli, G., H. Koivuluoto, M. Honkanen, M. Vippola, L. Lusvarghi, P. Vuoristo: Study of Cr3C2-based HVOF- and HVAF-Sprayed Coatings: Microstructure and Carbide Retention, Journal of Thermal Spray Technology, 26, 6, Aug. 2017, p. 1-18.
A. Vardelle, C. Moreau, J. Akedo, H. Ashrafizadeh, C. C. Berndt, J. Berghaus, M. Boulos, J. Brogan, A. Bourtsalas, A. Dolatabadi, M. Dorfman, T. Eden, P. Fauchais, G. Fisher, F. Gaertner, M. Gindrat, R. Henne, M. Hyland, E. Irissou, E. Jordan, K. Khor, A. Killinger, Y. Lau, C.-J. Li, L. Li, J. Longtin, N. Markocsan, P. Masset, J. Matejicek, G. Mauer, A. McDonald, J. Mostaghimi, S. Sampath, G. Schiller, K. Shinoda, M. Smith, A. Syed, N. Themelis, F.-L. Toma, J. Trelles, R. Vassen, P. Vuoristo: The 2016 Thermal Spray Roadmap. Journal of Thermal Spray Technology 25, 1376–1440 (2016). https://doi.org/10.1007/s11666-016-0473-x
H. Pajukoski, J. Näkki, S. Thieme, J. Tuominen, S. Nowotny, P. Vuoristo: High performance corrosion resistant coatings by novel coaxial cold- and hot-wire laser cladding methods, by 2016 In : Journal of Laser Applications. 28, 1, 012011.
L.-M. Berger, P. Ettmeyer, P. Vuoristo, T. Mäntylä, W. Kunert, Microstructure and Properties of WC-10%Co-4%Cr Spray Powders and Coatings. I. Powder Characterization, Journal of Thermal Spray Technology, 10 (2), 2001, 311.
Bolelli, B. Bonferroni, H. Koivuluoto, L. Lusvarghi, P. Vuoristo, Depth-sensing indentation for assessing the mechanical properties of cold-sprayed Ta, Surface & Coatings Technology, 205 (7), 2010, p. 2209.
J. Nurminen, J. Näkki, P. Vuoristo, Microstructure and properties of hard and wear resistant MMC coatings deposited by laser cladding. International Journal of Refractory Metals and Hard Materials, 27 (2), 2009, p. 472.
M. Kotilainen, K. Mizohata, M. Honkanen, P. Vuoristo, Influence of microstructure on temperature-induced ageing mechanisms of different solar absorber coatings, Solar Energy Materials & Solar Cells, 120, 2014, 462.
Dr. Sakari Pallaspuro works as postdoctoral researcher at the Materials and Mechanical Engineering at the University of Oulu. His research focuses on the microstructural and fracture mechanical aspects of novel high-strength steels.
D.Sc. (Tech) in Materials Science. Working with all sort of metals and alloys and improving their performance and reliability of machines and systems in different, usually challenging, environments. Especially experienced in corrosion research and testing, permanent magnet materials, microstructural studies and problem solving.
My research focus is on tribology, which investigates the friction, wear and lubrication of contacting surfaces as well as related fundamental failure mechanisms. This gives basis to provide advanced tribological expertise and solutions for developing future design concepts for machine elements and frictional joints to improve their performance, service life and operation monitoring. This work is done with close collaboration with industry using high standard numerical and experimental methods. Main current research interests are fretting induced friction, wear and fatigue in frictional joints as well as lubricated rolling/sliding contacts in gears and bearings related to combustion engines, mineral crushers and gear drives in wind turbines and marine applications. Advanced tribological contact design improves energy efficiency, power density and reliability of machine elements and systems having essential contribution to Finnish industrial competiveness and sustainable development.
Tribology (friction, wear and lubrication) and tribological machine elements in general - focusing on
- Fretting induced friction, wear and fatigue in frictional joints
- Lubricated rolling/sliding contacts in machine elements such as gears and bearings
Materials Science and Environmental Engineering
Professor, Materials Science, Tribology and Machine Elements, 2014 –
Professor, TUT, Machine Design, Mechanical Power Transmission and Tribology, 1999 –2013
Docent – Tribology, TUT, 1997-2002
R&D and Project Manager in private sector 1989-1996
Dr. Tech., TUT (Tampere University of Technology), 1989
Bayat R., Lehtovaara A., EHL/mixed transition of fully formulated environmentally acceptable gear oils, Tribology International 146 (2020) 12 p., 106158.
Hintikka J., Mäntylä A., Vaara J., Frondelius T., Lehtovaara A., Stable and unstable friction in fretting contacts, Tribology International, 131 (2019) 73-82.
Nurmi V., Hintikka J., Juoksukangas J., Honkanen M., Vippola M., Lehtovaara A., Mäntylä A., Vaara J., Frondelius T., The formation and characterization of fretting-induced degradation layers using quenched and tempered steel. Tribology International 131 (2019) 258-267.
Juoksukangas J., Lehtovaara A., Mäntylä A., Experimental and numerical investigation of fretting fatigue behavior in bolted joints, Tribology International 103 (2016) 440-448.
Linjamaa A., Lehtovaara A, Larsson R., Kallio M, Söchting S., Modelling and Analysis of Elastic and Thermal Deformations of a Hybrid Journal Bearing. Tribology International 118 (2018) 451-457.
Savolainen M., Lehtovaara A., An approach to investigating subsurface fatigue in a rolling/sliding contact, International Journal of Fatigue 117 (2018) 180-188
Kleemola J., Lehtovaara A., Experimental simulation of gear contact along the line of action, Tribology International 42 (2009) 1453-1459.
I am responsible of the research services and the infrastructure of Tampere Wear Center and the materials characterization facilities. In addition, I work as a coordinator of Wear Forum that is a collaboration network between TWC, research institutes, and companies. My particular research interests are the high stress abrasive and impact wear of steels, characterization of wear mechanisms, and assessment of the relevance of laboratory wear test methods in regard of the in-service performance of steels and other wear resistant materials. I have over 60 peer-reviewed scientific articles and about 70 other scientific publications, including conference papers with h-index 16 (Scopus).
Valtonen, K., Ojala, N., Haiko, O., Kuokkala, V.-T. Comparison of various high-stress wear conditions and wear performance of martensitic steels, Wear 426–427:3-13(2019).
Chintha, A.R., Valtonen, K. Kuokkala, V.-T., Kundu, S. Peet, M., Bhadeshia, H.K.D.H. Role of fracture toughness in impact-abrasion wear, Wear 428–429:430-437(2019).
Valtonen, K., Ratia, V., Ramakrihnan, K.R., Apostol, M., Terva, J., Kuokkala, V.-T., Impact wear and mechanical behavior of steels in subzero conditions. Tribology International 129:476-493(2019).
Valtonen, K., Keltamäki, K., Kuokkala, V.-T., High-stress abrasion of wear resistant steels in the cutting edges of loader buckets, Tribology International 119: 707–720(2018).
Valtonen, K., Ratia, V., Ojala, N., Kuokkala, V.-T., Comparison of laboratory wear test results with the in-service performance of cutting edges of loader buckets, Wear 388-389:93-100(2017).
Ojala, N., Valtonen, K., Minkkinen, J. & Kuokkala, V.-T. Edge effect in high speed slurry erosion wear tests of steels and elastomers, Wear 388-389:126-135(2017).
Ojala N., Valtonen K., Antikainen, A., Kemppainen, A., Minkkinen, J., Oja, O., Kuokkala V.-T. Wear performance of quenched wear resistant steels in abrasive slurry erosion, Wear 354-355:21-31(2016).
Oksanen, V., Valtonen, K., Andersson, P., Vaajoki, A., Laukkanen, A., Holmberg, K. & Kuokkala, V. T. 2015. Comparison of laboratory rolling-sliding wear tests with in-service wear of nodular cast iron rollers against wire ropes, Wear 340-341:73-81(2015).
Lindroos, M., Valtonen, K., Laukkanen, A., Holmberg, K., Kuokkala, V-T., Kemppainen, A., Wear behavior and work hardening of high strength steels in high stress abrasion, Wear 322-323:32-40(2015).
Ojala, N., Valtonen K., Heino V., Kallio M., Aaltonen J., Siitonen P. & Kuokkala, V.-T., Effects of composition and microstructure on abrasive wear performance of quenched wear resistant steels, Wear 317(1–2): 225–232(2014).
Ojala, N., Valtonen, K., Kivikytö-Reponen, P., Vuorinen, P., Siitonen, P. & Kuokkala, V.-T., The effect of test parameters on large particle high-speed slurry erosion testing, Tribology - Materials, Surfaces & Interfaces 8(2):98-104(2014).
Ratia, V., Valtonen, K., Kemppainen, A., Vippola, M., Kuokkala, V.-T., High-Stress Abrasion and Impact-Abrasion Testing of Wear Resistant Steels, Tribology Online 8(2):152-161(2013).