Tribochemical Behavior of Si3N4–hBN Ceramic Materials with Water Lubrication

Abstract

The main objective of this article is to study the tribological behavior of Si 3 N 4 -hBN composites with different hexagonal boron nitride (hBN) volume fraction under distilled water lubrication. Water-lubricated sliding tests were carried out on a pin-on-disc tester, and Si 3 N 4 was used as friction pair. The results showed that the addition of hBN to Si 3 N 4 resulted in a severe decrease of the friction coefficient, from 0.35 for Si 3 N 4 against Si 3 N 4 to 0.01 for Si 3 N 4 -20% hBN against Si 3 N 4 with drip-feed water lubrication; the friction coefficients of Si 3 N 4 -hBN/ Si 3 N 4 pairs sliding with full immersion water lubrication were as low as 0.01. The morphological and chemical characterization of the worn surfaces were conducted using scanning electron microscopy (SEM), laser scanning microscope, X-ray photoelectron spectroscopy (XPS). The analysis indicated that, with drip-feed water lubrication, hBN in Si 3 N 4 -hBN was spalled off during the wearing tests and spalling pits were formed on the wearing surface of Si 3 N 4 -hBN composites, then the wear debris were dropped into the pits and reacted with water, and thus a tribochemical film was formed on the wearing surface. The tribochemical film facilitated the wear surfaces of Si 3 N 4 -hBN and Si 3 N 4 to smooth with drip-feed water lubrication, while the tribochemical remove facilitated the wear surfaces to smooth with full-immersion water lubrication.

Tribological Properties of Si3N4-hBN Composite Ceramics Bearing on GCr15 under Seawater Lubrication

“…When the speed was 1.73 m/s and a load of 10N in dry friction conditions, the friction coefficient measured was around 0.12 for the Si 3 N 4 -10 vol% hBN/ASS (austenitic stainless steel) tribopair [16,17]. However, in drip-feed water lubricating condition, the friction coefficient of Si 3 N 4 -20 vol% hBN decreased from 0.35 to 0.01 [18]. Furthermore, with the increase of hBN to 10 vol% at a relative humidity RH of 55~65%, the friction coefficient and wear rate were further reduced respectively to 0.03 and 10 −6 mm 3 /Nm [19,20].…”

“…In the case a B 4 C ceramic matrix after adding hBN, the friction coefficient lowered from 0.373 for the B 4 C/B 4 C tribopair to 0.005 for the B 4 C-20 wt% hBN/B 4 C tribopair in water lubricating condition [15]. In our previous research [16][17][18][19][20], we studied the tribological performances of Si 3 N 4 -hBN bearing on stainless steel at different sliding speeds and with a normal load. When the speed was 1.73 m/s and a load of 10N in dry friction conditions, the friction coefficient measured was around 0.12 for the Si 3 N 4 -10 vol% hBN/ASS (austenitic stainless steel) tribopair [16,17].…”

MICROSTRUCTURE, MECHANICAL PROPERTIES AND FRICTION/WEAR BEHAVIOR OF HOT-PRESSED Si₃N₄/ BN CERAMIC COMPOSITES

“…The authors also found that the friction coefficient was not influenced by BN addition to Si 3 N 4 /BN composites. However, our previous research showed that Si 3 N 4 /BN composites (micro-sized) showed better tribological properties [10][11][12][13][14]. Especially, a lower friction coefficient (0.03) and wear rates of order 10 -6 were obtained for a sliding pair of Si 3 N 4 /BN composite and stainless steel, which is attributed to the formation of a self-lubricating film composed of SiO 2 , H 3 BO 3 and Fe 2 O 3 .…”

Enhanced thermal shock response of Al2O3–graphite composites through a layered architectural design

“…Nevertheless, the introduction of the lubricating phase severely destroys the continuity of the ceramic phase, thus resulting in a large amount of defects. The intrinsic brittleness of ceramics and extremely sensitivities to the presence of defects lead to poor mechanical properties of the ceramics, which subsequently limit the application of such kind of materials as wear‐resistance components in harsh working conditions.…”