Tribological behaviour of borided H13 steel with different boriding agents

Abstract

Solid boriding thermochemical treatment was carried out on AISI H13 steel. Two boriding agents were used: Ekabor 1-V2 commercial powder and a mixture of 73?26 wt-% borax, 24?06 wt-%SiC, 1?22 wt-%NH 4 Cl and 1?46 wt-%NaCl. Pin on disc wear tests were carried out to investigate tribological behaviour. After the wear tests, samples were cut in cross-section to evaluate the thickness and morphology of the boride layer by scanning electron microscopy (SEM) and Vickers microhardness. Wear mechanisms were evaluated by SEM. A large improvement in wear resistance was observed for borided samples compared with samples that had been quenched and tempered. The thickness of the borided layer was higher for samples borided with Ekabor powder than those borided with the mixture. In comparison with quenched and tempered samples, borided samples had a higher incidence of cracks, which favours spalling and reduction of grooves formed by abrasive wear.

Microstructural and tribological characterization of niobium boride coating produced on AISI 1020 steel via multicomponent boriding

“…This fact indicates that, since niobization is a material deposition treatment, the surface characteristics of the borided samples are maintained during the deposition of the niobium atoms and diffusion of the boron atoms from the substrate to the formation of a superficial layer of niobium borides on the sample surface. The increase in roughness parameters after the boriding thermochemical treatment (before niobization), as found in this work, is in agreement with other works [36,37]. The values measured for skewness (positive) and kurtosis (>3) are attributed to profiles with many high peaks and low valleys [38].…”

Effect of Boride Layer on PM HSS AISI M2 on the Mechanisms Acting in the Transverse Rupture Strength Test

“…Silica sand was placed on the cover to prevent gas escape during boriding. Boriding cycle follows parameters found in Krelling's work 22 ; the samples are heated to a temperature of 1000 °C and maintained at this temperature for 2 hours. Cooling was performed in air to room temperature to avoid excessive grain growth.…”

HVOF-sprayed Coating Over AISI 4140 Steel for Hard Chromium Replacement

“…When the harder phases (WC, W 2 C) are pressed against a ductile matrix (CoCr) during the sliding contact, deformations occur in the matrix (white arrow indicated in Figure 10d) and embrittlement of the harder particles takes place. In this process, the matrix is extruded out of the surface of the coating by the compression of abrasive particles and little deformation capacity of the harder phases 36 . With the continuity of this event, there is the pull out of carbide phases due to extrusion of Co phase from the coating 17 .…”

“…The tribolayer process formation on a wear surface is associated with the presence of a binding element that adheres to this adjacent surface 37 . Part of the extruded matrix may have been adhered to the counter body and to the small imperfections (pores and cracks) of the wear surface 36 . In contrast, abrasive micro-particles may bond together again through this adhered matrix and initiate the process formation of a tribolayer 24,38 .…”

“…In this dense and well compacted new layer 19 , cobalt acts by promoting the cohesion of the hard particles and fixing the film to the wear surface. The formed tribolayer protects the surface against new damages, reducing the wear rate to a lower value than the initial one 36 .…”