Investigation of hBN powder lubricating characteristics of die steel H13–ceramic Si3N4 tribopair at 800 ℃

Author(s):  
Yi Zhang ◽  
Wei Wang ◽  
Zhaowen Hu ◽  
Kun Liu ◽  
Jingjing Chang

In the background that hot-working die steels have been widely used in the hot stamping process of high strength steels for manufacturing car bodies and parts, solid lubricant materials are promising for decreasing the friction and wear on die surfaces at high temperatures. In this work, hexagonal boron nitride was used to lubricate the sliding interface of ceramic Si3N4 against die steel H13 at 800 ℃, and its frictional behavior was investigated at different contact pressures and rotating speeds by pin-on-disk testing. Tribological characteristics of hexagonal boron nitride solid lubricant were analyzed through 3D laser scanning confocal microscope and energy-dispersive spectroscopy. The results show that the wear behavior of hexagonal boron nitride powder lubricating film featured two stages: gradual undermining and complete damage. The formation-broken dynamic cycle of partial lubricating film constantly occurred at the frictional interface until the film was completely destroyed. In a short period, the hexagonal boron nitride lubricant can reduce the friction coefficient efficiently compared with dry friction, and the die substrate showed basically no abrasion because a layer of plasticity accumulated on the die surface, which protected the substrate. In a certain range, the boundary-lubricating film became damaged rapidly with increasing load, and high speed was not conducive to the stability of the lubricating film.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hitesh Agarwal ◽  
Bernat Terrés ◽  
Lorenzo Orsini ◽  
Alberto Montanaro ◽  
Vito Sorianello ◽  
...  

AbstractElectro-absorption (EA) waveguide-coupled modulators are essential building blocks for on-chip optical communications. Compared to state-of-the-art silicon (Si) devices, graphene-based EA modulators promise smaller footprints, larger temperature stability, cost-effective integration and high speeds. However, combining high speed and large modulation efficiencies in a single graphene-based device has remained elusive so far. In this work, we overcome this fundamental trade-off by demonstrating the 2D-3D dielectric integration in a high-quality encapsulated graphene device. We integrated hafnium oxide (HfO2) and two-dimensional hexagonal boron nitride (hBN) within the insulating section of a double-layer (DL) graphene EA modulator. This combination of materials allows for a high-quality modulator device with high performances: a ~39 GHz bandwidth (BW) with a three-fold increase in modulation efficiency compared to previously reported high-speed modulators. This 2D-3D dielectric integration paves the way to a plethora of electronic and opto-electronic devices with enhanced performance and stability, while expanding the freedom for new device designs.


2021 ◽  
pp. 67-70
Author(s):  

The effect of a solid lubricant on the wear of cubic boron nitride grinding wheels on a ceramic bond of different hardness and grain size in the processing of high-speed steel is investigated. The dependences of the change in the wear of cubic boron nitride on the parameters of the processing mode are determined. An automated calculation system is proposed to control the consumption of cubic boron nitride grinding wheels in production conditions. Keywords: solid lubricant, grinding, high speed steel, cubic boron nitride grinding wheel, consumption, wear, grinding mode. [email protected]


2021 ◽  
Author(s):  
M. Oechsner ◽  
T. Engler ◽  
H. Scheerer ◽  
Y. Joung ◽  
K. Bobzin ◽  
...  

Abstract High-velocity oxyfuel (HVOF) sprayed coatings of Cr3C2-NiCr containing solid lubricants such as nickel cladded graphite and hexagonal boron nitride were successfully developed and characterised with the aim of optimizing their friction and wear behaviour. HVOF technology was used for the integration of solid lubricants to achieve strong cohesion between particles while minimizing thermal decomposition. Coating microstructure and composition were measured and correlated to the results of tribological and corrosion tests. The integration of the solid lubricant greatly reduced friction and wear volume at room temperature, but the lubricating effect was highly dependent on atmosphere and temperature. Cr3C2-NiCr with hBN, however, tends to exhibit more stable wear resistance over a wider temperature range and can be used at temperatures beyond 450 °C.


2011 ◽  
Vol 257 (23) ◽  
pp. 10195-10200 ◽  
Author(s):  
Yuxia Cao ◽  
Lingzhong Du ◽  
Chuanbing Huang ◽  
Wei Liu ◽  
Weigang Zhang

2011 ◽  
Vol 697-698 ◽  
pp. 80-83
Author(s):  
L.Y. Ding ◽  
Hong Hua Su ◽  
H.J. Xu ◽  
M. Fan

It is essential to control the heat generated in the cutting zone in order to ensure the workpiece quality after grinding. This article deals with an investigation in using graphite and hexagonal boron nitride as solid lubricants to reduce friction and thereby improve the surface integrity of Ti-6Al-4V alloy. The polymer-based solid lubricant coating wheels have been prepared. Grinding experiments have been conducted to study the effect of the graphite and hexagonal boron nitride lubricants on the grinding temperature and the surface quality of the workpiece while grinding Ti-6Al-4V. Results indicate that there is a considerable improvement in the performance of grinding Ti-6Al-4V using graphite and hexagonal boron nitride as solid lubricants in dry grinding in terms of grinding temperature and surface quality of the work piece. The indigenous polymer-based solid lubricant coatings are effective in dry grinding.


2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Fatih Aydin ◽  
M. Emre Turan

Abstract The goal of the study is to examine the dry sliding wear behavior of pure Mg and Mg/nano-boron nitride (BN) composite at elevated temperatures. The wear behavior of the samples was evaluated under loads of 5, 10, and 20 N, at sliding speed of 80, 130, and 180 mm s−1 and at temperatures of 25, 100, and 175 °C. The examination of worn surface, counterface, and wear debris was performed. The results showed that nano-BN particles lead to substantial enhancement of wear resistance for both room and elevated temperatures. Mg/0.25 BN has lower coefficient of friction values due to the presence of BN which act as solid lubricant. The wear mechanisms are thermal softening, melting, oxidation, abrasion, and delamination.


2017 ◽  
Vol 890 ◽  
pp. 98-102 ◽  
Author(s):  
Sourabh Paul ◽  
Amitava Ghosh

Small quantity cooling lubrication (SQCL) with commercially available metal working fluids (MWF) and nanofluids has been attempted successfully in machining and grinding. Solid lubricants also provided some benefits in grinding of metallic alloys. However, there are very few studies using molybdenum di-sulphide (MoS2) and hexagonal boron nitride (hBN) dispersed nanofluids applied in SQCL mode in grinding. The aim of the present work is to experimentally study improvement in grinding of EN31 steel using alumina grinding wheel with aqueous MoS2 and hBN nanofluids. The grinding study is supported by detailed tribometry at 1 m/s sliding speed to reveal the possible reasons behind such improvement. MoS2 dispersed nanofluids provided minimum coefficient of friction in ball-on-disc test. It also provided the maximum reduction in specific grinding energy and improvement in surface finish with respect to flood cooling. hBN dispersed nanofluids could not match the performance of MoS2 dispersed nanofluids both in ball-on-disc and grinding experiments.


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