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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Dry Sliding Wear Resistance of Cobalt Boride Coatings Formed on ASTM F1537 Alloy

New results about the wear resistance of CoB-Co{sub 2}B coatings under dry sliding conditions were estimated in this work. The cobalt boride coatings were developed at the surface of the ASTM F1537 alloy by means of the powder-pack boriding process using two experimental conditions: 1223 K with 6 h of exposure and 1273 K with 10 h of exposure. Before the sliding wear tests, Vickers depth-sensing microindentation tests were conducted on the cross section of the cobalt boride coatings to estimate the distribution of hardness, Young’s modulus, and residual stresses. Otherwise, the sliding wear tests were performed on both boriding conditions and on the untreated material, using a ball-on-flat configuration comprised of an alumina ball as a counterpart with applied loads between 5 and 20 N. The wear rates of the borided ASTM F1537 alloy were ranged between 4.02 and 8.91 × 10{sup −6} mm{sup 3} N{sup −1} m{sup −1} compared with the values of the untreated material (13.90 and 15.78 × 10{sup −6} mm{sup 3} N{sup −1} m{sup −1}) for the overall set of experimental conditions; nevertheless, the influence of boriding conditions (1273 K with 10 h of exposure) tended to increase the CoB coating thickness, developing a more brittle layer that decreased the sliding wear resistance at the surface of the borided ASTM F1537 alloy. Finally, the presence of failure mechanisms on the surface of the wear tracks was analyzed for both borided ASTM F1537 alloy and untreated material.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Wear and Why? How Ash Elements Can Help Define Wear Profiles of Biomass Feedstocks

Biomass feedstocks have been shown to cause high wear rates on biomass processing equipment, including grinders, pneumatic conveyance systems, and screw feeders. Previously, wear rates were positively correlated with ash concentrations. Physical and chemical properties, including ash content, vary across the anatomy of plants in biomass feedstocks. To better understand biomass tissues that cause the most wear, anatomical fractions of pine forest residues were tested for wear properties. Fractions were tested in the Accelerated Wear Testing Apparatus using steel coupon mass loss to evaluate wear rates. Extrinsic ash was extracted and characterized. Total ash content of the forest residue was 0.80wt%. Anatomical fractions showed varied amounts of ash with highest concentrations in bark and needles (2.33wt%, 3.52wt%, respectively). The wear rate of the forest residue was 2.36mg loss per kg biomass. Low ash fractions, including whitewood and cambium, caused little wear. Bark had lower ash than the needles but resulted in more wear (8.63 vs 5.57mg loss per kg biomass). Bark contained the most extrinsic ash and largest ash particle size, while needles contained the least extrinsic ash and smallest ash particle size. These findings indicate that total ash content (intrinsic plus extrinsic), soil contamination, and elemental analysis can provide information related to wear properties of biomass materials; however, these analyses do not fully explain the differences observed in the wear rates of bark and needles. Additional testing is to determine other parameters of importance.

Lacey, Jeffrey A.↗
DOE OSTI2020

Multifunctional Tunable Polymethacrylates for Enhanced Shear Stability and Wear Prevention

This paper describes the design, synthesis, and characterization of linear, polar, and non-polar polymethacrylates designed for use as lubricant viscosity index improvers with enhanced shear and anti-wear resistance. The polymers were prepared via Reversible Addition-Fragmentation Chain Transfer (RAFT) to obtain relatively low, narrow, molecular weights, with random polar moieties. The resulting polymers were evaluated as oil solutions to determine their viscosity index, shear stability performance, and antiwear characteristics. The polymers had molecular weights (Mw) ranging from 120-170 kDa, and the resulting viscosity indexes (VIs) in general tracked the Mw. Although the VIs were modest (140-189), all polymers displayed higher values than a commercial product designed for similar applications, both at 2% (w/w) and when kinematic viscosities (KVs) were normalized to the lowest KV100 of ~5cSt. One of the imidazole-containing polymers displayed an anomalously high VI for a low apparent Mw. As hypothesized, many of the polar polymers demonstrated substantial wear reduction compared to the non-polar homopolymers or a commercial benchmark. The low-molecular-weight imidazole-containing polymer produced less than 4% of the wear displayed by the commercial standard. The higher molecular weight polymers containing imidazole, hydroxy group and amino group also produced as little as 10% of the wear shown by the benchmark. The strategy demonstrated the benefit of low, narrow, molecular weight polymers to achieve good shear stability in viscosity modifiers while minimizing wear, rendering them suitable for fluid-power applications.

friction modifiers↗
DOE OSTI2017

Study on Composition, Microstructure and Wear Behavior of Fe-B-C Wear-Resistant Surfacing Alloys

Fe-B-C alloy layers with various microstructures were welded on Q235 steel plates using welding powders/H08Mn2Si and welding wires composite surfacing technology. The relationship existing between the chemical composition, microstructure and wear resistance of the surfacing alloy layers was investigated by scanning electron microscopy, x-ray diffraction, electron backscatter diffraction and wear tests. The results demonstrated that the volume fractions and morphologies of the microstructures in the surfacing alloy layers could be controlled by adjusting the boron and carbon contents in the welding powders, which could further regulate the wear resistance of the surfacing alloy layers. The typical microstructures of the Fe-B-C surfacing alloy layers included dendritic Fe, rod-like Fe{sub 2}B, fishbone-like Fe{sub 2}B and daisy-like Fe{sub 3}(C, B). The wear resistance of the alloy layers with various morphologies differed. The wear resistance order of the different microstructures was: rod-like Fe{sub 2}B > fishbone-like Fe{sub 2}B > daisy-like Fe{sub 3}(C, B) > dendritic Fe. A large number of rod-like Fe{sub 2}B with high microhardness could be obtained at the boron content of 5.70 ~ 5.90 wt.% and the carbon content of 0.50 ~ 0.60wt.%. The highest wear resistance of the Fe-B-C alloy layers reached the value of 24.1 g{sup −1}, which demonstrates the main microscopic cutting wear mechanism of the Fe-B-C alloy layers.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Friction- and Wear-Reducing Properties of Multifunctional Small Molecules

Nitrogen- and oxygen-containing compounds were designed and synthesized, and their tribological performance as multifunctional base oils (MFBOs) for internal combustion engine applications was evaluated. Two of the compounds displayed good rheology without the addition of polymeric viscosity modifiers, with a high viscosity index (VI) above 200.Additionally, all three MFBOs had lower coefficients of friction when compared to well established and accepted benchmarks, and demonstrated wear improvement by a factor of 5.5 to 70 compared to either of the benchmarks. Moreover, the compounds were easily synthesized in one step from commercial intermediates or starting materials. This work demonstrates that careful design of a single molecule might provide the functions of base oil, viscosity modifiers (or viscosity index improvers), anti-wear and friction reducing additives.

Cosimbescu, Lelia↗
DOE OSTI2017

Global energy consumption due to friction and wear in the mining industry

Calculations on the global energy consumption due to friction and wear in the mineral mining industry are presented. For the first time, the impact of wear is also included in more detailed calculations in order to show its enormous tribological and economic impacts on this industry. A large variety of mining equipment used for the extraction, haulage and beneficiation of underground mining, surface mining and mineral processing were analysed. Coefficients of friction and wear rates of moving mechanical assemblies were estimated based on available information in literature in four general cases: (1) a global average mine in use today, (2) a mine with today's best commercial technology, (3) a mine with today's most advanced technology based upon the adaptation of the latest R&D achievements, and (4) a mine with best futuristic technology forecasted in the next 10 years.

Energy↗
DOE OSTI2019

Influence of Wear Test Parameters on the Electrical Contact Performance of Brass Alloy/Copper Contactors Under Fretting Wear

Fretting of mated electronic connectors may be due to extreme increase in contact resistance. We present a detailed analysis of contact resistance by fretting experiments using brass alloys/copper contact pairs. The relationship between wear mechanisms and contact resistance was determined. The influence of fundamental factors such as normal load, displacement amplitude, and current on contact resistance change was also evaluated. It was found out that displacement amplitude, normal load, and current are important parameters for infinite lifetime or stable electrical resistance during fretting condition. Influence of displacement amplitude on the electrical contact performance might be affected by wear debris in the contact area. Electric contact performance could be improved by increasing the power current, which could break down the thick oxide film formed. The predicted working lifetime and reliability requirements of the connector were determined to optimize and extend the service life under the working condition.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Application of an Erosion Wear Model to Predict Wear of Hammer Milling Components

A workable analytical erosion model that relates critical hammermill process parameters (hammermill geometry and rotational speed) to critical material attributes of inorganic mineral species in feedstock (density, size, and aspect ratio) and substrate (hardness, toughness, and fatigue ductility) was applied to model wear (more specifically, change in the shape of hammers) in hammer milling operations. Results of the model were compared to experimental observations of the shape of hammers used in the INL Stage 1 Vermeer hammermill. Results showed good agreement between predicted and measured shape of the hammer, and that a quality-by-design (QbD) approach can be developed to predict component reliability based on scientific engineering principles in lieu of trial-and-error approaches.

36 MATERIALS SCIENCE↗
DOE OSTI2021

In situ friction and wear behavior of rubber materials incorporating various fillers and/or a plasticizer in high-pressure hydrogen

Polymers are used routinely for equipment and infrastructure in hydrogen vehicle refueling stations, but significant gaps remain in understanding their hydrogen compatibility. The tribological properties of these materials in a high-pressure hydrogen environment is important in preventing component failure and the need for frequent replacement. We present in situ tribological studies on model rubbers, which include common fillers and plasticizer, using an in situ tribometer developed previously. Results suggest a clear, yet complicated, combined effect of the high-pressure hydrogen and the additives on the tribological performance of the chosen materials, as compared to matching experiments performed in ambient air. We find that the additives improved wear resistance in EPDM but deteriorated that in NBR due to disparate additive-polymer interactions.

Kuang, Wenbin↗
DOE OSTI2019

Effect of Micro-Arc Oxidation on Friction–Wear Behavior of Cold-Sprayed Al Coating in 3.5 wt.% NaCl Solution

A cold-sprayed Al coating on S355 steel was processed using micro-arc oxidation (MAO). The friction–wear behavior of the obtained coating in 3.5 wt.% NaCl solution was investigated using a wear test, and the effects of wear loads and speeds on the friction–wear performances of the MAO coating were analyzed. The results show that the MAO coating is primarily composed of Al{sub 2}O{sub 3}, with no other phases. The average coefficients of friction (COFs) of the MAO coating under the wear loads of 0.5, 1.0 and 1.5 N are 0.48, 0.62, and 0.76, respectively, and the corresponding wear rates are 4.20 × 10{sup −5}, 4.21 × 10{sup −5} and 4.27 × 10{sup −5} mm{sup 3} m{sup −1} N{sup −1}, exhibiting the higher wear resistance. Under the wear load of 1.0 N, the average COFs of the MAO coating at the wear speeds of 5.0, 6.7 and 8.3 Hz are 0.32, 0.45 and 0.62, respectively; and the corresponding wear rates are 3.21 × 10{sup −5}, 3.49 × 10{sup −5} and 4.21 × 10{sup −5} mm{sup 3} m N{sup −1}, respectively, which increase with the increase in wear speeds. The wear mechanism of the MAO coating is fatigue wear and abrasive wear, and its wear resistance was better than the cold-sprayed Al coating.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Wear behavior of Al 0.6 CoCrFeNi high-entropy alloys: Effect of environments

Environment can impact the wear behavior of metals and alloys substantially. The tribological properties of Al 0.6 CoCrFeNi high-entropy alloys (HEAs) were investigated in ambient air, deionized water, simulated acid rain, and simulated seawater conditions at frequencies of 2–5 Hz. The as-cast alloy was composed of simple face-centered cubic and body-centered cubic phases. The wear rate of the as-cast HEA in the ambient air condition was significantly higher than that in the liquid environment. The wear resistance in seawater was superior to that in ambient air, deionized water, and acid rain. Both the friction coefficient and wear rate in seawater were the lowest due to the formation of oxidation film, lubrication, and corrosion action in solution. The dominant wear mechanism in the ambient air condition and deionized water was abrasive wear, delamination wear, and oxidative wear. Here by contrast, the wear mechanism in acid rain and seawater was mainly corrosion wear, adhesive wear, abrasive wear, and oxidative wear.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Wear Behavior of an Ultra-High-Strength Eutectoid Steel

Wear behavior of an ultra-high-strength AISI 1080 steel developed through incomplete austenitization-based combined cyclic heat treatment is investigated in comparison with annealed and conventional hardened and tempered conditions against an alumina disk (sliding speed = 1 m s{sup −1}) using a pin-on-disk tribometer at a load range of 7.35-14.7 N. On a gross scale, the mechanism of surface damage involves adhesive wear coupled with abrasive wear (microcutting effects in particular) at lower loads. At higher loads, mainly the abrasive wear (both microcutting and microploughing mechanisms) and evolution of adherent oxide are observed. Besides, microhardness of matrix increases with load indicating substantial strain hardening during wear test. The rate of overall wear is found to increase with load. As-received annealed steel with the lowest initial hardness suffers from severe abrasive wear, thereby exhibiting the highest wear loss. Such a severe wear loss is not observed in conventional hardened and tempered and combined cyclic heat treatment conditions. Combined cyclic heat-treated steel exhibits the greatest wear resistance (lowest wear loss) due to its initial high hardness and evolution of hard abrasion-resistant tribolayer during wear test at higher load.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Tungsten Inert Gas Arc Remelting on Microstructure and Wear Properties of Plasma-Sprayed NiCr-Cr{sub 3}C{sub 2} Coating

In this work, a NiCr-Cr{sub 3}C{sub 2} coating was prepared on an AISI 1045 steel substrate by plasma spraying and then remelted with the tungsten inert gas (TIG) arc method. The purpose was to study the effects of TIG remelting treatment on the microstructure, mechanical properties and wear properties of a plasma-sprayed NiCr-Cr{sub 3}C{sub 2} coating. The results show that after TIG remelting, the density of the coating increased, the internal porosity decreased from 8.1 to 0.2%, and the number of cracks and inclusions greatly reduced. The hardness of the coating also became uniform and increased from 1007 to 1141 HV{sub 0.1}, with an obvious increase of 13.3%, and the fracture toughness increased by 321.3%. The wear volume after TIG remelting at room temperature was reduced by 59.5%, and the wear pattern changed from brittle fracture and abrasive wear to abrasive wear and adhesive wear. The wear loss at 700 °C was also reduced by 43.6%, and the wear pattern was transformed from brittle fracture and fatigue wear caused by oxidation to oxidative wear and adhesive wear. Therefore, TIG remelting treatment can effectively improve the microstructure, mechanical properties and wear resistance of a plasma-sprayed NiCr-Cr{sub 3}C{sub 2} coating.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Identification of biomass fractions responsible for wear on biomass processing equipment

Abstract: There is a current problem in the DOE supported Integrated Bio refineries where metal parts, including grinder blades and pneumatic ducting, are wearing out too early in the lifetime of the equipment. Repairing and replacing the equipment leads to unexpected equipment costs and the complete shutdown of the affected production lines.. It is believed that the ash content of the biomass is the likely cause of the wear on the metals. To address this ongoing problem, INL staff are analyzing the wear of metals caused by interactions with biomass . A sandblaster was modified to shoot ground biomass at metal coupons to simulate the wear that is occurring in the bio refineries. This system was able to test several variables including which biomass causes erosive and abrasive wear, impingement angle, particle densities of the biomass, and how the quantity of mass impacts the wear of the metals. Coupon mass loss after blasting was used to evaluate the wear caused by different biomass fractions. It was determined that the bark fraction of biomass caused the most wear and the whitewood fraction caused the least wear. Coupon mass loss in logging residues was found to be positively correlated with ash content, indicating that the ash content in the biomass is responsible for wear. It was also found that hand separated forest residues, sodium, aluminum and iron were positively correlated with wear, while silicon showed no correlation with wear.

09 BIOMASS FUELS↗
DOE OSTI2019

Dry Sliding Wear Behavior and Mechanism of a Hot-Dip Aluminized Steel as a Function of Sliding Velocity

Fe-Al intermetallic coatings were prepared on AISI 1045 steel by hot-dip aluminizing and subsequent high-temperature diffusion. The dry sliding wear tests were performed for the aluminized steel with various substrate hardnesses in the velocity range of 0.75-4 m/s on a pin-on-disk configuration. The dry sliding wear behavior and mechanisms of the aluminized steel under various velocities were explored. It was found that the wear rate decreased substantially with an increase in sliding velocity from 0.75 to 1.5 and then slightly varied in the velocity range of 1.5-4 m/s. The wear behavior and mechanisms of the aluminized steel were noticed to be closely related with tribo-layers. As tribo-layers contained more oxides with Fe{sub 2}O{sub 3}, the wear resistance of the aluminized steel was markedly improved because of their protective function. The substrate hardness also changed the wear behavior of the aluminized steel by affecting the stability of tribo-layers because the substrate hardness was inversely proportional to the thermal stability of the substrate structure. Under a low velocity of 0.75 m/s, adhesive wear and abrasive wear prevailed owing to the metal-on-metal contact, resulting in a higher wear rate. At 1.5-4 m/s, mild oxidative wear prevailed due to the stable existence of tribo-oxides layers. However, at 1.5 and 4 m/s for the substrate hardness of 45 HRC, the wear rate was slightly increased because the protection of tribo-layers was weakened by a double-layered structure or more cracks in tribo-layers and coatings.

36 MATERIALS SCIENCE↗