Comparison of hardmetal and hard chromium coatings under different tribological conditions

Wank, Andreas; Wielage, B.; Pokhmurska, H.; Friesen, E.; Reisel, Guido

doi:10.1016/j.surfcoat.2006.04.058

Cited by 42 publications

(21 citation statements)

References 7 publications

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“…Specifically, the largest increase in hardness occurs from 2 to 3 torch scans, whereas, at higher number of scans, the increase is less remarkable. The hardness of the 2-scan coating is significantly lower than the values reported in the pertinent literature for analogous HVOF-sprayed WC-CoCr coatings [13,25], whereas the hardness of the coatings with 3 or more scans approaches or overcomes 1100HV 0.1 , which is comparable to goodquality cermet coatings [13,25]. The presence or absence of the Ni bond coat (samples with bond coat are identified by the label "bc") does not affect the hardness of WC-CoCr layers significantly, except, maybe, for the 2-scan coating.…”

Section: Microstructural and Micromechanical Characterizationcontrasting

confidence: 56%

“…Particularly, HVOF-sprayed WC-based cermets (e.g. WC-Co, WC-CoCr) have been shown to possess excellent tribological properties [13][14][15][16]; indeed, they combine very high hardness with satisfactory toughness [11,17], as Co-based metal matrixes possesses ductility and excellent wettability toward the carbide grains. Accordingly, WC-based coatings on steel substrates have already been technically validated as an alternative to hard chrome plating, particularly for the most severe operating conditions [13,14,16,18].…”

Section: Introductionmentioning

confidence: 99%

“…WC-Co, WC-CoCr) have been shown to possess excellent tribological properties [13][14][15][16]; indeed, they combine very high hardness with satisfactory toughness [11,17], as Co-based metal matrixes possesses ductility and excellent wettability toward the carbide grains. Accordingly, WC-based coatings on steel substrates have already been technically validated as an alternative to hard chrome plating, particularly for the most severe operating conditions [13,14,16,18]. The nature of the substrate (for instance, steel vs. aluminium), generally speaking, can affect the outcome of every coating process, but, in the case of thermal spraying techniques, this influence is not too large, so that it may be reasonably conjectured that HVOF-sprayed WC-based coatings can also offer good tribological properties when deposited onto Al substrates [2], even though some differences, in comparison to the traditional steel substrates, are likely to exist.…”

Section: Introductionmentioning

confidence: 99%

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HVOF-sprayed WC–CoCr coatings on Al alloy: Effect of the coating thickness on the tribological properties

Bolelli

Lusvarghi

Barletta

2009

Wear

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a b s t r a c tThe microstructure, the micromechanical properties, the wear behaviour and the impact resistance of WC-CoCr cermet coatings, deposited onto an aluminium alloy substrate by High Velocity Oxygen-Fuel (HVOF) flame-spraying, were examined as a function of the coating thickness, which was varied between 50 m and 150 m by performing different numbers of scans of the HVOF torch in front of the substrate. The coatings became denser and significantly harder as the number of torch scans increased: the analysis of single WC-CoCr splats by combined SEM and Focused Ion Beam (FIB) techniques enabled the interpretation of the mechanisms underlying this phenomenon. In accordance to such densification, the sliding wear resistance increased with the number of torch scans, as abrasive grooving and brittle failure mechanisms were progressively suppressed. The resistance to cyclic impact was also enhanced. In comparison to anodised films, the WC-CoCr coatings appeared much more resistant against wear and cyclic impact; specifically, three torch scans seem enough to produce a coating having suitable characteristics.

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Section: Microstructural and Micromechanical Characterizationcontrasting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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HVOF-sprayed WC–CoCr coatings on Al alloy: Effect of the coating thickness on the tribological properties

Bolelli

Lusvarghi

Barletta

2009

Wear

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“…This relationship between hardness and microabrasion wear processes is important when considering surface treatments, as higher hardness coatings should lead to reduced wear. However, it has also been shown that coarser carbides perform better than finer carbides in microabrasion (Ref 42,43). The proposed process suggests that in microabrasion, the binder phase is removed preferentially, followed by carbide grain pull-out.…”

Section: Resultsmentioning

confidence: 98%

Improving Tribological Properties of Cast Al-Si Alloys through Application of Wear-Resistant Thermal Spray Coatings

Culliton¹,

Betts²,

Carvalho

et al. 2013

J Therm Spray Tech

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Flame Spray Thermal Spray coatings are low-cost, high-wear surface-treatment technologies. However, little has been reported on their potential effects on cast automotive aluminum alloys. The aim of this research was to investigate the tribological properties of as-sprayed NiCrBSi and WC/12Co Flame Spray coatings applied to two cast aluminum alloys: high-copper LM24 (AlSi8Cu3Fe), and low-copper LM25 (AlSi7Mg). Potential interactions between the mechanical properties of the substrate and the deposited coatings were deemed to be significant. Microstructural, microhardness, friction, and wear (pin-on-disk, microabrasion, Taber abrasion, etc.) results are reported, and the performance differences between coatings on the different substrates were noted. The coefficient of friction was reduced from 0.69-0.72 to 0.12-0.35. Wear (pin-on-disk) was reduced by a factor of 10 3 -10 4 , which was related to the high surface roughness of the coatings. Microabrasion wear was dependent on coating hardness and applied load. Taber abrasion results showed a strong dependency on the substrate, coating morphology, and homogeneity.

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“…Peculiar microstructures are thus obtained, different from those of conventional thermally sprayed coatings and having improved thermomechanical behavior (for instance, better thermal cycling resistance for thermal barrier coatings) ( Ref 1,2,13). Moreover, the very small lamella size can result in much better coating surface finish, reducing or eliminating the need for costly machining operations (near-net-shape manufacturing) ( Ref 8,9,14). Heat-sensitive materials, which could be altered by ordinary thermal spray processes, can largely preserve their desired chemical and structural properties when deposited by these techniques.…”

Section: Introductionmentioning

confidence: 99%

Microstructural and Tribological Investigation of High-Velocity Suspension Flame Sprayed (HVSFS) Al2O3 Coatings

et al. 2008

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Al 2 O 3 coatings were manufactured by the high-velocity suspension flame spraying (HVSFS) technique using a nanopowder suspension. Their structural and microstructural characteristics, micromechanical behavior, and tribological properties were studied and compared to conventional atmospheric plasma sprayed and high-velocity oxygen-fuel-sprayed Al 2 O 3 coatings manufactured using commercially available feedstock. The HVSFS process enables near full melting of the nanopowder particles, resulting in very small and well flattened lamellae (thickness range 100 nm to 1 lm), almost free of transverse microcracking, with very few unmelted inclusions. Thus, porosity is much lower and pores are smaller than in conventional coatings. Moreover, few interlamellar or intralamellar cracks exist, resulting in reduced pore interconnectivity (evaluated by electrochemical impedance spectroscopy). Such strong interlamellar cohesion favors much better dry sliding wear resistance at room temperature and at 400°C.

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Comparison of hardmetal and hard chromium coatings under different tribological conditions

Cited by 42 publications

References 7 publications

HVOF-sprayed WC–CoCr coatings on Al alloy: Effect of the coating thickness on the tribological properties

HVOF-sprayed WC–CoCr coatings on Al alloy: Effect of the coating thickness on the tribological properties

Improving Tribological Properties of Cast Al-Si Alloys through Application of Wear-Resistant Thermal Spray Coatings

Microstructural and Tribological Investigation of High-Velocity Suspension Flame Sprayed (HVSFS) Al2O3 Coatings

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