Tribological evaluation of self-lubricating sintered steels

Campos, K.R.; Kapsa, Ph.; Binder, Cristiano; Klein, Aloı́sio Nelmo; Mello, José Daniel Biasoli de

doi:10.1016/j.wear.2015.01.056

Cited by 22 publications

(16 citation statements)

References 30 publications

(55 reference statements)

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“…Further reduction in the friction coefficient was observed when 3% SiC was . Graphite associated with graphite powders and nodular cast iron is characterised as a 3D graphite and is highly aligned according to the literature [48]. The spectrum of the graphite nodules produced by the SiC decomposition clearly showed a D and a D′ band (associated with crystallinity disorder).…”

Section: Metal Injection Mouldingmentioning

confidence: 68%

“…As well described in previous works [2,15,48,82], carbonyl iron powder was mixed with the elemental powder of the alloying elements to produce iron-based composites. Varying amounts of SiC powder (1, 2, 3, 4, and 5 wt% SiC) were also added.…”

Section: Metal Injection Mouldingmentioning

confidence: 99%

“…The spectrum of the graphite nodules produced by the SiC decomposition clearly showed a D and a D′ band (associated with crystallinity disorder). The analysis of the spectra [15,48,68] showed strong evidence of the presence of turbostratic 2D graphite, including widening of the bands, the ID/IG ratio, the size of the graphite crystallites and the shape of the second-order G′ band. The large interplanar distances (≥3.499 Å vs. 3.354 Å for the highly aligned 3D graphite) between the graphene foils and the misorientation of these foils were confirmed by TEM, as illustrated in Fig.…”

Section: Metal Injection Mouldingmentioning

confidence: 99%

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Tribological behaviour of sintered iron based self-lubricating composites

et al. 2017

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This work is a review of previous works, presenting and discussing the most important results obtained by an ongoing research program towards the development of innovative, low-cost, self-lubricating composites with a low friction coefficient and high mechanical strength and wear resistance. Special emphasis is given to uniaxial die pressing of solid lubricant particles mixed with matrix powders and to metal injection moulding associated with in situ generation of solid lubricant particles. Initially, a microstructural model/ processing route (powder injection moulding followed by plasma-assisted debinding and sintering) produced a homogeneous dispersion of in situ generated solid lubricant particles. Micrometric nodules of graphite with diameter smaller than 20 μm were formed, constituting a nanostructured stacking of graphite foils with nanometric thickness. Micro Raman analysis indicated that the graphite nodules were composed of turbostratic 2D graphite having highly misaligned graphene planes separated by large interlamellae distance. Large interplanar distance between the graphene foils and misalignment of these foils were confirmed by transmission electron microscopy and were, probably, the origin of the outstandingly low dry friction coefficient (0.04). The effect of sintering temperature, precursor content, metallic matrix composition and surface finish is also reported. Furthermore, the influence of a double-pressing/double-sintering (DPDS) technique on the tribological performance of self-lubricating uniaxially die-pressed hBN + graphite-Fe-Si-C-Mo composite is also investigated. Moreover, the tribological behaviour of die-pressed Fe-Si-C matrix composites containing 5, 7.5 and 10 wt% solid lubricants (hBN and graphite) added during the mixing step is analysed in terms of mechanical properties and wear mechanisms. Finally, the synergy between solid lubricant particles dispersed in a metallic matrix and fluid lubricants in a cooperative mixed lubrication regime is presented.

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Section: Metal Injection Mouldingmentioning

confidence: 68%

Section: Metal Injection Mouldingmentioning

confidence: 99%

Section: Metal Injection Mouldingmentioning

confidence: 99%

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Tribological behaviour of sintered iron based self-lubricating composites

et al. 2017

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“…This graphite has been found to be turbostratic 13 : turbostratic graphite consist of disordered graphene layers with random parallel stacking without three dimensional order 14 . Turbostratic graphite provides lower friction coefficients than crystalline graphite as found by Kumar et al 15 this explains the low friction coefficients and wear rates found by previous studies 11,16 therefore, studying the structural changes in these nodules became relevant to evaluate the feasibility to perform heat treatments and retain or improve the tribological behavior of these materials.…”

Section: Introductionmentioning

confidence: 91%

“…Statistical analysis of the ID/IG ratios shows that there is no statistically significant difference between the samples as determined by one-way ANOVA (F(3,56) = 1.769, p = 0.05) which means that even if the means of the ID/IG ratio differs between conditions it cannot be concluded with a 95% confidence that the heat treatments had an impact on the structure of the graphite nodules measured by Raman spectroscopy, therefore, for these materials, heat treatments can be used to improve the mechanical properties of these materials without significantly affecting the turbostratic structure of the graphite derived from SiC dissociation 10 thus maintaining its ability to provide solid lubrication 16 .…”

Section: (4)mentioning

confidence: 99%

Effect of Heat Treatments and SiC Content in the Mechanical Properties and Microstructure of Self-Lubricating Steels

et al. 2017

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The objective of the present work was to study the effect of heat treatments in the microstructure, graphite nodules and mechanical properties of self-lubricating steels, to achieve this, self-lubricating steels (Fe + 0.45C + 4Ni + 1Mo % wt ) and additions of 2 and 3 % wt SiC were fabricated. They were consequently heat treated in 3 different conditions: martempering at 180 °C and tempering at 530 °C and 300 °C respectively and austempering at 300 °C. Hardness, yield strength, tensile strength and work hardening behavior were studied in as-sintered and heat-treated samples. The microstructure was analyzed by optical microscopy, scanning electron microscopy, Raman spectroscopy and microhardness. The transformation temperatures were determined using dilatometric tests. Results show that the presence of dissolved Si in the matrix due to SiC dissociation notably affects the morphology of the microstructure and transformation temperatures also affecting post heat treatment mechanical properties. The structure of graphite nodules produced by SiC dissociation is nott significantly affected by the heat treatments.

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