Microstructure and tribological properties of plasma sprayed alumina and alumina-graphite coatings

Marcinauskas, Liutauras; Mathew, Joseph; Milieška, Mindaugas; Thanigachalam, Balakumaran; Kupec, Alja; Česnavičius, Ramūnas; Kėželis, Romualdas; Kalin, Mitjan

doi:10.1016/j.surfcoat.2018.06.081

Cited by 18 publications

(26 citation statements)

References 41 publications

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“…Chen et al [15,32] observed a similar relationship, the increase in the graphite content from 5 to 20 wt.% in sprayed powder also resulted in a significant decrease in the hardness of Cu/graphite and Cu/Al 2 O 3 /graphite cold-sprayed coatings. In general, the presence of graphite inside the metal matrix or metal-ceramic matrix reduces the hardness of the obtained composites, which is the result of its low hardness and poor interfacial bonding strength with the matrix components [11,15,32]. However, some authors reported an increase in hardness with an increase of the graphite content in sprayed blends [16,33,37].…”

Section: Analysis Of the Taguchi Experiments For Hardness Of Cr3c2-25(ni20cr)/ni-25 Graphite Coatingsmentioning

confidence: 99%

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Optimization of Mechanical Properties of Cr3C2-Ni20Cr/Graphite Cold Sprayed Coatings

et al. 2021

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This study analyzed the mechanical properties of cold-sprayed Cr3C2-25(Ni20Cr) blended with Ni-graphite as a solid lubricant deposited on 7075 aluminum alloy substrate. To optimize the coating properties, different sets of parameters (graphite content in feedstock, process gas composition, spraying distance, and traverse gun speed) were tested in the frame of the Taguchi experiment. The cold-sprayed coatings were evaluated for their chromium carbide and graphite content, hardness, and coefficient of friction. Analysis of the microstructure of the deposited coatings revealed that graphite as a soft and brittle component fills all voids in the coating and its quantity depends on its content in the feedstock. The experimental results show that the composition of the process gas has the greatest impact on the Cr3C2 content in the coating and the proportion of graphite in the sprayed blend directly affects its hardness. In the case of the coefficient of friction, the most significant parameters were the graphite content in the sprayed blend, the spraying distance, and process gas composition. The conducted verification experiment with the optimum parameter values allowed a coating with the highest hardness and the lowest coefficient of friction to be obtained.

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Section: Analysis Of the Taguchi Experiments For Hardness Of Cr3c2-25(ni20cr)/ni-25 Graphite Coatingsmentioning

confidence: 99%

“…Graphite is widely used as a solid lubricant and is constantly being researched in thermally sprayed coatings [10][11][12][13]. Its use in composite coatings sprayed with cold gas, where the influence of heat is very limited, enables the formation of coatings with new properties.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Mechanical Properties of Cr3C2-Ni20Cr/Graphite Cold Sprayed Coatings

et al. 2021

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“…The normalized wear rate for A and A5Z coatings were found to be practically immeasurable, due to a mere plastic deformation, but with A10Z, it was found to be 2.64 x 10 -5 mm 3 /Nm. The reasons for the lowest friction coefficient and wear rate as in the pure alumina coatings could be mainly due to the presence of a strong phase: γ-Al 2 O 3 , brought forth due to the α→γ transformations from well-melted particles aiding a better surface morphology subject to efficient substrate cooling [7]. With respect to the alumina-zirconia A5Z coatings, the well-spread tetragonal phase which aids in the formation of a stronger and tougher matrix, could have been seen in application here [6].…”

Section: Resultsmentioning

confidence: 99%

“…The coatings were deposited on stainless steel substrates (AISI 304L) using a direct current plasma torch operating at atmospheric pressure. The plasma torch herein was constructed at the Lithuanian Energy Institute [7]. The steel substrates (s) had dimensions of 40x10x1.5 mm.…”

Section: Methodsmentioning

confidence: 99%

Tribological Properties of Alumina-Zirconia Composite Coatings Prepared by Plasma Spraying

Mathew¹,

Marcinauskas²,

Milieška³

et al. 2019

PES

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The intent of this research was to determine the tribological trends of zirconia as an additive to a plasma-sprayed alumina coating matrix. For the deposition process, pure alumina and alumina-withzirconia (5%, 10%) weight percentages were employed to be coated on steel substrates using an airhydrogen plasma. The torch power was set to ~40 kW. The surface roughness for the alumina coatings were in the range from 2.6-3.2 µm and with additive percentages of zirconia, it was found to vary between 3.0-3.7 µm. XRD measurements indicated that the predominant phase in the alumina-zirconia coatings was tetragonal-ZrO 2 (t-ZrO 2 ) and with alumina, it was α-Al 2 O 3 and γ-Al 2 O 3 . The tribological properties such as the friction coefficient and the wear-rate of the alumina-composite coatings had been inspected to evaluate its dependence on the type and concentration of the additive powders. An increase in friction-coefficient was observed with the addition of zirconia. The normalized wear rates were in the range of ~10 -5 mm 3 /Nm for the composite coatings with certain exceptions.

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“…However, despite their high hardness, the alumina coatings are brittle and have relatively high friction coefficients under dry sliding conditions. In order to improve the toughness, brittleness, thermal or tribological properties of alumina coatings, various additives such as ZrO 2 [7][8][9][10], TiO 2 [7,11], graphite [12], and graphene nanoplatelets [13] are used.…”

Section: Introductionmentioning

confidence: 99%

Improvement of the Tribological Properties of Alumina Coatings by Zirconia Addition

et al. 2021

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Al2O3 and Al2O3-ZrO2 coatings were deposited on stainless steel using atmospheric plasma spraying. The influence of arc current and zirconia addition on the surface morphology of the coating, phase composition and tribological properties under dry sliding conditions were investigated. The addition of zirconia reduced the surface roughness of the coatings. The X-ray diffraction measurements indicated that the Al2O3 coatings were composed of β-Al2O3, α-Al2O3, and γ-Al2O3 phases. The addition of zirconia led to the formation of tetragonal and monoclinic phases of zirconia in the as-sprayed coatings. The friction coefficients of Al2O3 and Al2O3-ZrO2 coatings were similar and varied in the range of 0.72–0.75. The specific wear rates of the as-sprayed coatings were reduced with the increase of arc current. It was obtained that the wear rates of the Al2O3-ZrO2 coatings were at least three times lower compared to Al2O3 coatings.

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Microstructure and tribological properties of plasma sprayed alumina and alumina-graphite coatings

Cited by 18 publications

References 41 publications

Optimization of Mechanical Properties of Cr3C2-Ni20Cr/Graphite Cold Sprayed Coatings

Optimization of Mechanical Properties of Cr3C2-Ni20Cr/Graphite Cold Sprayed Coatings

Tribological Properties of Alumina-Zirconia Composite Coatings Prepared by Plasma Spraying

Improvement of the Tribological Properties of Alumina Coatings by Zirconia Addition

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