Residual Stress in HVOF Thermal Sprayed Coatings(1st Report). In-situ Measurement of Stress Generation during HVOF Thermal Spraying.

Abstract This work is devoted to the study of peculiarities of thermal sprayed coatings behavior under conditions of cavitation, as well as the elaboration of compositions of cavitation-resistant coatings and technology for their application with the aim of engine cylinders sleeves protection from cavitation-erosion destruction. The methods of arc metallization, flame and plasma spraying were used for coatings deposition. Powders of metal alloys and oxides, mechanical mixtures of nickel alloys with carbides, wires and flux-cored wires were applied as materials for thermal spraying. Method of magneto-striction vibration was used to determine the coatings cavitation resistance. A correlation between a bond strength of coatings and the character of their cavitation destruction was established. The best results were obtained in the case of using stainless steel wires and flux-cored wires using. Resistance of coated diesel engines sleeves was increased 1.6 times in comparison with sleeves without coatings. Semi-automatic line for arc metallization of diesel sleeves with a production of 600,000 sleeves per year was designed, build up and put into operation.

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Thermal Spray Processing of WC-Co Nanomaterials

Thermal Spray 2000: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc2000p0895 ◽

2000 ◽

Author(s):

J. Voyer ◽

B.R. Marple

Keyword(s):

Phase Composition ◽

Recent Work ◽

Phase Analysis ◽

Thermal Spraying ◽

Volume Percent ◽

Wear Properties ◽

Lower Porosity ◽

Hvof Thermal Spraying ◽

Spray Processing ◽

Sprayed Coatings

Abstract WC-Co based cermets are extensively used in wear applications due to their hardness and toughness. Recent work has demonstrated the potential for using nanoscale constituents to improve the wear properties of these materials. In the present study, two WC-Co powders containing a nanosized WC phase were used to produce coatings by HVOF thermal spraying. These powders had similar properties except for the volume percent binder present: WC-8C0 and WC-12Co. The thermal spraying conditions were varied in order to identify their effect on the microstructure, properties and phase composition of the sprayed coatings. The as-sprayed coatings possess porosity values ranging between 1% and 2% and microhardness values (HV100) from 1150 to 1550, which are quite similar to values obtained for conventionally sized WC-based coatings. For all the coatings, phase analysis indicated significant degradation of the WC phase to produce W2C, W, CO3W3C and Co6W3C. For some spray conditions, even WO3 phase was found in the coatings. The JP-5000 HVOF system produces coatings with lower porosity, similar microhardness values and, more importantly, with lower WC degradation than the coatings produced with the DJ-2700.

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Development of Nanostructured Al2O3-Ni HVOF Coatings

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.317-318.539 ◽

2006 ◽

Vol 317-318 ◽

pp. 539-544 ◽

Cited By ~ 6

Author(s):

Simo Pekka Hannula ◽

Erja Turunen ◽

Jari Keskinen ◽

Tommi Varis ◽

Teppo Fält ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Spraying ◽

Al2o3 Coating ◽

Hvof Spraying ◽

Protective Properties ◽

Hvof Coatings ◽

Hvof Thermal Spraying ◽

Plasma Sprayed Coatings ◽

Plasma Sprayed ◽

Sprayed Coatings

HVOF thermal spraying has been developed to deposit dense Al2O3-coatings for improved protective properties. As compared to generally used plasma sprayed coatings HVOF coatings can be prepared much denser and thus are better suited for applications where protective properties of the coating are needed. In this paper we describe the development of HVOF spraying technologies for nanocrystalline Al2O3- and Al2O3-Ni-coatings. The microstructure and the mechanical properties of these novel coatings are reported and compared to a conventionally processed Al2O3-coating.

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Influence of a Filler Composition and Conditions of Flame Spraying on a Structure and Mechanical Properties of Composite Polymer Coatings

Thermal Spray 1997: Proceedings from the United Thermal Spray Conference ◽

10.31399/asm.cp.itsc1997p0239 ◽

1997 ◽

Author(s):

Yu. Borisov ◽

V. Korzhik ◽

I. Sviridova ◽

A. Skorokhod

Keyword(s):

Mechanical Properties ◽

Thermal Spraying ◽

Polymer Coatings ◽

Flame Spraying ◽

Composite Polymer ◽

Filled Polymers ◽

Physico Chemical ◽

Mechanical And Service Properties ◽

Sprayed Coatings ◽

Thermal Sprayed Coatings

Abstract In thermal spraying of metal-polymer coatings, the processes of polymers oxidation and destruction can have special features, as the temperature of heating of the filler particles can significantly exceed the temperature of destruction of the polymer binder. Hence, the need to study the features of the process of formation of thermal sprayed coatings from filled polymers and their physico-chemical, mechanical and service properties. This paper describes the influence of a filler composition and conditions of flame spraying on a structure and mechanical properties of composite polymer coatings. It is observed that addition of 5-10 vol. % of Fe-Ni-B alloy powder to low-pressure polyethylene polymer matrices, improves the wear resistance of thermal sprayed coatings 1.2-1.3 times under the conditions of gas-abrasive wear, compared to purely polymer coating, owing to the combination of the higher hardness of the coating with the high damping properties of the polymer matrix.

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A Stretch/Bend Method for In Situ Measurement of the Delamination Toughness of Coatings and Films Attached to Substrates

Journal of Applied Mechanics ◽

10.1115/1.4001938 ◽

2010 ◽

Vol 78 (1) ◽

Cited By ~ 2

Author(s):

M. Y. He ◽

J. W. Hutchinson ◽

A. G. Evans

Keyword(s):

Residual Stress ◽

Energy Release Rate ◽

Energy Release ◽

Release Rate ◽

Beam Theory ◽

Companion Paper ◽

In Situ Measurement ◽

Delamination Toughness ◽

Slender Beams

A stretch/bend method for the in situ measurement of the delamination toughness of coatings attached to substrates is described. A beam theory analysis is presented that illustrates the main features of the test. The analysis is general and allows for the presence of residual stress. It reveals that the test produces stable extension of delaminations, rendering it suitable for multiple measurements in a single test. It also provides scaling relations and enables estimates of the loads needed to extend delaminations. Finite element calculations reveal that the beam theory solutions are accurate for slender beams, but overestimate the energy release rate for stubbier configurations and short delaminations. The substantial influence of residual stress on the energy release rate and phase angle is highly dependent on parameters such as the thickness and modulus ratio for the two layers. Its effect must be included to obtain viable measurements of toughness. In a companion paper, the method has been applied to a columnar thermal barrier coating deposited onto a Ni-based super-alloy.

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