The correlation between wear evolution and mechanical property degradation of wire rope in a multi-layer winding system

Surface wear is one of the major causes of damage to wire ropes in multi-layer winding systems. This damage leads to performance degradation and affects the service safety of wire rope. To reveal the wear evolution and the performance degradation of wire rope in service, the correlations between the wear characteristic parameters and the residual strength were investigated. The results show that the variation in the wear parameters is affected by the wear distribution and the structure of the wire rope. The main wear mechanisms between wire ropes are adhesion wear and abrasive wear. Different wear parameters should be combined to evaluate the wear state of the wire rope. The tensile temperature rise could accurately reflect the wear evolution of the in-service wire rope under the condition of a large wear degree. The negative correlation between the residual strength and the wear area of the damaged rope samples is the strongest.

Study on the Properties of Coated Cutters on Functionally Graded WC-Co/Ni-Zr Substrates with FCC Phase Enriched Surfaces

Currently, the research on mechanical behavior and cutting performance of functionally graded carbides is quite limited, which limits the rapid development of high-performance cemented carbide cutting tools. Based on WC-Co-Zr and WC-Ni-Zr, this study synthesized two kinds of cemented carbide cutters, i.e., the cemented carbide cutters with homogeneous microstructure and functionally graded carbide (FGC) cutters with FCC phase ZrN-enriched surfaces. Furthermore, TiAlN coating has been investigated on these carbide cutters. Mechanical behavior, friction, wear performance, and cutting behavior have been investigated for these coated carbides and their corresponding substrates. It was found that, as compared with coated cutters on WC-Co/Ni-Zr carbide substrates with homogeneous microstructures, the coated cutters on WC-Co/Ni-Zr FGC substrates with FCC phase-enriched surfaces show higher wear resistance and cutting life, and the wear mechanism during cutting is mainly adhesion wear.

Tribological study of a polymer bushing wear with a steel axle for an automatic car tensioner

This paper aims to show through a factorial experimental design significant factors on the polymeric bushing wear PA66, including their amplitude, frequency and spring height, when interacting with a steel axle SAE1018 (from Society of Automotive Engineers - SAE) in a tension belt applied. It was verified that factors as amplitude and frequency are significant and it was possible to propose a mathematical model to predict this wear behaviour for the proposed test. Moreover, an adhesion wear behaviour was verified, whereof a polyamide film was observed on the axle transferred by the bushing. Through the microscopy report analysis, it was possible to see the transfer film topology characterisation for a better comprehension of the adhered polyamide film from the bushing to the axle surface.

Influence of Tool Wear on Form Deviations in Dry Machining of UNS A97075 Alloy

Geometrical tolerances play a very important role in the functionality and assembly of parts made of light alloys for aeronautical applications. These parts are frequently machined in dry conditions. Under these conditions, the tool wear becomes one of the most important variables that influence geometrical tolerances. In this work, the influence of tool wear on roundness, straightness and cylindricity of dry-turned UNS A97075 alloy has been analyzed. The tool wear and form deviations evolution as a function of the cutting parameters and the cutting time has been assessed. In addition, the predominant tool wear mechanisms have been checked. The experimental results revealed that the indirect adhesion wear (BUL and BUE) was the main tool-wear mechanism, with the feed being the most influential cutting parameter. The combination of high feed and low cutting speed values resulted in the highest tool wear. The analyzed form deviations showed a general trend to increase with both cutting parameters. The tool wear and the form deviations tend to increase with the cutting time only within the intermediate range of feed tested. As the main novelty, a relationship between the cutting parameters, the cutting time (and, indirectly, the tool wear) and the analyzed form deviations has been found.

Effects of inert gas environment on the sliding wear behavior of AZ91/B4C surface composites

Tribological characteristics of AZ91/B4C surface composites were studied under air and argon gas environments. Tests were conducted under a constant normal load of 10 N, with a sliding velocity of 0.06 m/s using a linear reciprocating tribometer. Wear tracks and debris were analyzed using scanning electron microscopy, three-dimensional contour topography, and energy-dispersive X-ray spectroscopy in order to understand the wear mechanisms. The wear rate of the specimen tested under the argon environment was found to be lower (∼60%) in comparison with that of the specimen tested under the open-air environment. The value of the friction coefficient was found to be minimum under the argon environment compared with the air environment. In the air environment, the major material loss from the test specimen was attributed to oxidation wear; whereas under the argon environment, strain-hardening effect was dominant, and the material was found to be removed by delamination wear. In addition, the worn surface morphology of the wear tracks and counter surfaces showed the involvement of abrasion and adhesion wear mechanisms. The results of the study pave the pathway for the design of lightweight surface composite material systems such as AZ91/B4C toward an efficient and robust tribo-pair applicability for a controlled environment.

Effect of Variation of SiC Reinforcement on Wear Behaviour of AZ91 Alloy Composites

In this investigation, the extensive wear behaviour of materials was studied using SiC reinforced magnesium alloy composites fabricated through the stir casting process. The wear properties of AZ91 alloy composites with a small variation (i.e., 3%, 6%, 9% and 12%) of SiC particulates were evaluated by varying the normal load with sliding velocity and sliding distance. The worn surfaces were examined by scanning electron microscope to predict the different wear mechanisms on the pin while sliding on the hard disk in the dry sliding wear test condition. The microhardness of the SiC reinforced AZ91 composites was found to be more than the un-reinforced AZ91 alloy. Pins tested at load 19.62 N, and 2.6 m/s exhibited a series of short cracks nearly perpendicular to the sliding direction. At higher speed and load, the oxidation and delamination were observed to be fully converted into adhesion wear. Abrasion, oxidation, and delamination wear mechanisms were generally dominant in lower sliding velocity and lower load region, while adhesion and thermal softening/melting were dominant in higher sliding velocity and loads. The wear rate and coefficient of friction of the SiC reinforced composites were lower than that of the unreinforced alloy. This is due to the fact of higher hardness exhibited by the composites. The wear behaviour at the velocity of 1.39 m/s was dominated by oxidation and delamination wear, whereas at the velocity of 2.6 m/s the wear behaviour was dominated by abrasion and adhesion wear. It was also found that the plastic deformation and smearing occurred at higher load and sliding velocity.

Milling Performance of Fluorinated Surfactants-Based Coating Tools in Processing Particleboard

To investigate the cutting performance of tools with fluorinated surfactant-based coatings, the milling performance of melamine-coated particleboard was characterized by means of the cutting force, tool wear and surface quality. A scanning electron microscope (SEM) and a three-dimensional super field microscope were used to observe the morphologies of coated and uncoated tool wear and machined surfaces. The results showed that (1) the surface wettability of the coated tool is lower than that of the uncoated tool; (2) the main wear mechanisms for tools with a fluorinated surfactant-based coating are abrasive wear and microchipping. The fluorinated surfactant-based coating acts as a solid lubricant, which can obviously reduce adhesion wear; (3) the surface roughness obtained by machining using coated tools is much smaller than that found for uncoated tools.

Study on the Biotribological Properties of Ti6Al7Nb and Ultra High Density Molecular Weight Polyethylene at Different Lubricant Temperature

Higher frictional heat will be produced during the service process of artificial hip joint prosthesis in vivo than natural joint, which would cause the rise of the temperature of synovial fluid and the change of the wear resistance of prosthetic materials. In this work, the biotribological properties of ZrO2/Ti6Al7Nb and ZrO2/UHMWPE pairs at different lubricant temperatures were investigated. The results show that there is a strong correlation between the wettability and average friction coefficient of Ti6Al7Nb, while there is also a strong correlation between the wettability and mass loss of UHMWPE. The wear loss of Ti6Al7Nb and UHMWPE decreases gradually and the friction coefficient increases gradually as the lubricant temperature rises from 20 ℃ to 46 ℃, which is mainly affected by the precipitation process of protein. As a protective layer, it can reduce the wear rate, but as a third body, it can participate in the friction process and increase the friction coefficient. The characteristics of lubricant change greatly at 60 ℃, but the increase of temperature is not the only reason for the precipitation of synovial protein. The synergistic effect with the friction process results in a significant change on the wear mechanism of Ti6Al7Nb and UHMWPE under this condition. The wear mechanism of Ti6Al7Nb is mainly abrasive wear and adhesion wear at different lubricant temperature. With the increase of lubricant temperature, the proportion of adhesion wear mechanism becomes larger. Due to the low thermal deformation temperature and thermal conductivity, the wear mechanism of UHMWPE changed obviously at 60 ℃, and the wear morphology is mainly plastic deformation.

Room and High Temperature Tribological Performance of Multilayered TiSiN/TiN and TiSiN/TiN(Ag) Coatings Deposited by Sputtering

In this study, we compare the tribological performance of a multilayer TiSiN/Ti(Ag)N coating with a TiSiN/TiN coating with a similar Si content in order to demonstrate the effect of the solid lubricant phase, silver. For Al2O3 balls, the hardness and reduced modulus determine the tribological performance of the coatings for tests conducted at room temperature (RT) against Al2O3 balls. At 550 °C, the TiSiN/TiN coating failed, whereas the Ag-containing coating performed better due to the presence of Ag in the contact, which decreased the shear stress and, consequently, the friction. For tests against TiAl6V4 balls, the Ag-containing coating was always better than the TiSiN/TiN one. At 550 °C, Ag in the wear track prevented the adhesion of the oxidized Ti-alloy wear debris in the contact, favoring the adhesion of wear debris from the coating to both the coating and counterpart surfaces. No wear could be measured for the 700 °C tests for both coatings due to different reasons: (i) the presence of oxidized adhered material from the ball to the reference TiSiN/TiN coating surface protected from wear and (ii) the presence of Ag-agglomerated particles decreased the friction and minimized the adhesion wear of the counterpart for the TiSiN/TiN(Ag) coating.

Possibilities for Using New Types of Additive Materials for Hardfacing

The paper presents the results of the research aimed at quality determination of cladding layers for renovation of the rollers during continuous casting of steel. Four newly designed additive materials in the form of filled tubular wires of diameter 2.4 mm were evaluated. Additive materials were experimentally designed for the renovation of support rollers of the hot rolling mill. The cladding layers were applied on 31CrMoV9 material (EN 10085). Method used in experimed was submarged cladding 121 - EN ISO 4063 SAW. A specially developed flux WLDC 17 was used. The structure of cladding layers, basic mechanical propertis and their chemical composition were determined. The JOEL JSM-7000F electron microscope was used for analysis. Layers were tested under tribological conditions with pin-on-disc adhesion wear. Tests were performed on a Bruker UMT 3 device. Observation and measurement of wear traces were performed on the Sensofar PLu Neox confocal microscope.