Tribological Properties Of Alloy Research Articles

Tribological properties of Fe(Cr)-B alloys at high temperature

This work is aimed to study the effect of boron on wear resistance of Fe-Cr-B alloys containing different boron contents (0 wt%, 5 wt%, 7 wt% and 9 wt%) from room temperature (RT) to 800 °C in order to explore their applications as high-temperature wear resistant mechanical parts. Additionally, the wear mechanism of alloys is evaluated. The tribological properties of alloys are systematically studied by using a ball-on-disc tribometer at 10 N and 0.20 m/s from RT to 800 °C sliding against Si3N4 ceramic ball. The boron element greatly improves the wear resistance of specimens as compared with that of unreinforced specimen. The friction coefficients of specimens decrease with increasing of testing temperature. The wear rates of Fe-Cr-B alloys decrease firstly and then raise with the increase of boron content. The specific wear rates of specimens with boron are 1/10 of the unreinforced specimen. Fe-21wt%Cr-7wt% B keeps the best tribological properties at high temperature.

Laser Cladding of γ-TiAl Intermetallic Alloy on Titanium Alloy Substrates

The enhancement of titanium and titanium alloy's tribological properties is of major interest in many applications such as the aerospace and automotive industry. Therefore, the current research paper investigates the laser cladding of Ti48Al2Cr2Nb powder onto Ti6242 titanium alloy substrates. The work was carried out in two steps. First, the optimal deposition parameters were defined using the so-called “combined parameters,” i.e., the specific energy E specific and powder density G. Thus, the results show that those combined parameters have a significant influence on the geometry, microstructure, and microhardness of titanium aluminide-formed tracks. Then, the formation of dense, homogeneous, and defect-free coatings based on optimal parameters has been investigated. Optical and scanning electron microscopy techniques as well as energy-dispersive spectroscopy and X-ray diffraction analyses have shown that a duplex structure consisting of γ-TiAl and α 2-Ti3Al phases was obtained in the coatings during laser cladding. Moreover, it was shown that produced coatings exhibit higher values of microhardness (477 ± 9 Hv0.3) and wear resistance (average friction coefficient is 0.31 and volume of worn material is 5 mm3 after 400 m) compared to those obtained with bare titanium alloy substrates (353 Hv0.3, average friction coefficient is 0.57 and a volume of worn material after 400 m is 35 mm3).

Friction and Wear Behavior of Fe–Cr–B Alloys in Liquid Paraffin Oil

The tribological properties of Fe–Cr–B alloys were studied sliding against SiC ball in liquid paraffin oil. The boron played an important role in improving tribological properties of alloys. The friction coefficients of alloys decreased with the increase of normal load and sliding speed. The Fe–Cr–B alloys showed better wear resistance than that of Fe–Cr alloy. Fe-21 wt.% Cr-7 wt.% B alloy had the best tribological properties. The wear mechanism of Fe–Cr alloy was abrasive wear and plastic deformation. The wear mechanism of Fe–Cr–B alloys was microploughing and fatigue flaking pits.

Co含量对一种Ni-Co-Al粉末高温合金摩擦学性能的影响

采用粉末冶金(机械合金化+真空热压烧结)制备不同Co含量的Ni-Co-Al系高温合金,并考察合金在800℃下的高温摩擦学性能与Co含量的变化关系。结果表明:适量的Co可以提高合金的硬度和抗压强度,并改善合金的摩擦学性能,但过量的Co(Co质量分数达到30%)又使合金的摩擦学性能变差。磨痕表面的扫描电子显微镜(SEM)和X射线光电子能谱(XPS)及能谱(EDS)分析表明,磨痕表面形成了由CoO等组成的氧化物釉质层。这层釉质层的成分及其在摩擦过程中的脱落程度影响了合金的高温摩擦学性能。

The features of influence of ZrO2 and WC nanodispersed additives on the properties of metal matrix composite

The features of influence of ZrO2 and WC nanoparticles on the properties of the iron-based metal matrix composite are investigated. The influence of nanoparticles on the compactibility of the powder material and mechanical and tribological properties of alloy is analyzed. It is revealed that the metal matrix composite particle reinforced with nanoparticles, which was fabricated by hot compression technology, is characterized by increased hardness and wear resistance.

The Tribological Properties of Mg Alloy Produced by ECAE and Laser Melting

A new processing procedure was applied to an Mg alloy. This procedure involves the equal channel angular extrusion (ECAE) process and laser melting surface treatment. A commercial Mg alloy was first produced by equal channel angular extrusion (ECAE) process. Then the laser melting surfave treatment was carried out after ECAE. The effects of ECAE and laser melting on tribological properties of the alloy were investigated. Experimental results showed that the mechanical properties and tribological properties of the alloy were improved after ECAE. The laser melting surface treatment can further improve the tribological properties of Mg alloy.

Influence of Corrosive Environment on Changes of the ZnAl40Cu3 Upper Alloy Layer

Zn-Al alloys are used mainly because of their tribological properties as a material alternative to bronze, cast iron and aluminum alloys in bearings, and as a structural material. Improved properties of Zn-Al alloys can be obtained by the addition of copper , silicon and using of heat treatment. Tribological properties of alloys of the Zn-Al-Cu alloys, their structure has been well described in the literature. Far less are, however, studies on the effect of corrosive environments on the structure of the surface layer of the alloy. The purpose of this examination was to determine the effect of corrosive environment on the surface layer of the ZnAl22Cu3 alloy. Subject of examination was the unmodified alloy containing 40% Al mass. and 3%. Cu (Zn - remain). The tested alloy was subject of the following operations: soaking at the temperature of 185°C during 10 hours with cooling in water, soaking at the temperature of 380°C during 10 hours with cooling in water and soaking at the temperature of 380°C w during10 hours with subsequent soaking at the temperature of 170°C with cooling in water. Subject of tests structural examination were samples after potentiostatic tests carried out at potential E = 300 mV Ekor in 24 hours in an acid rain, pH = 3.5. In order to determine the microstructure of the examined coatings metallographic examinations were performed using optical and scanning microscope cooperating with EDS X-ray spectrometer. Quantitative analysis of the selected characteristic microareas determined from X-ray spectral analysis EDX.

Effects of Al2O3 particle reinforcement on the lubricated sliding wear behavior of ZA-27 alloy composites

The present investigation deals with the effect of Al2O3 particle reinforcement on the lubricated sliding behavior of ZA-27 alloy. The composites with 3, 5, and 10 wt% of Al2O3 particles were produced by the compocasting procedure. Tribological properties of alloy and composites were studied, using block-on-disk tribometer at different specific loads and sliding speeds. The test results revealed that composite specimens exhibited significantly lower wear rate, but higher coefficient of friction than the matrix alloy specimens in all the combinations of applied loads and sliding speeds. The improved antiwear characteristics of the composites were influenced by positive effects of higher frictional heating on compatibility of the composite phases and suppressing micro-cracking tendency. Due to that, effects of reinforcing hard particles were manifested through the reduced wear rate of composites, especially in conditions of higher load, lower sliding speeds and higher Al2O3 particle content. In present wear tests, the significant forming of mechanically mixed layers was not noticed, what is confirmed by the SEM microphotographs.

Effects of Heat Treatment on Mechanical and Tribological Properties of Cobalt-Base Tribaloy Alloys

Cobalt-base Tribaloy alloys are important wear-resistant materials, especially for high-temperature applications, because of the outstanding properties of the strengthened cobalt solid solution and the hard Laves intermetallic phase that make up the alloys. The Laves intermetallic phase is so abundant (35–70 vol.%) in these alloys that its presence governs all of the material properties. Heat treatment may alter the volume fraction, the size/shape, and the distribution of the Laves phase in the microstructures as well as the phase and structure of the cobalt solid solution, thus influencing the mechanical and tribological properties of the alloys. In this work, the effects of heat treatment on two cobalt-based Tribaloy alloys, T-400 and T-200, were studied. The former is a well-known Tribaloy alloy, and the latter is a newly developed one. These two alloys were heat treated in different conditions. The phases and microstructures of the alloys before and after the heat treatments were analyzed using x-ray and scanning electron microscopy. The mechanical and tribological properties of the alloys were investigated using a nano-indentation technique and a pin-on-disc tribometer, respectively.

CrC·CaF2—A PVD stratified coating for friction and wear under heavy load at high temperature

This study is to enable a cobalt superalloy to work at 700°C in air under a normal load of 5500 N corresponding to a nominal pressure of 25 MPa. Preliminary experience shows that the cobalt superalloy does not have sufficient mechanical and tribological properties to support this load under sliding conditions. In fact, both the applied normal load and the induced tangential force rapidly damage the sliding surface. So it is necessary to modify its surface properties. The present study used a stratified coating with a hard layer made of chromium carbide (CrC) and a soft layer made of calcium fluoride (CaF2) for improving the alloy's tribological properties. All the coatings were deposited by PVD. The CrC layer has a thickness of 3 μm, and the CaF2 varies from 0 to 3 μm. In order to assess the tribological properties of the coatings, a reference couple consisting of a triboalloy PS212 to PS212 as well as three couples consisting of CrC to CrC, CrC·CaF2(0.6 μm) to CrC·CaF2(0.6 μm) and CrC·CaF2(3 μm) to CrC·CaF2(3 μm) have been tested at 500 and 700°C at ISMCM-CESTI using a specific high temperature tribometer FHTO (Frictiographe à Haute Température en atmosphère Oxydante). These tests have revealed that, by comparison to PS212, the stratified coatings have a slightly lower friction coefficient (0.28–0.32 instead of 0.35) and a significantly lower wear rate (30×10−6 mm3/Nm instead of 1000×10−6 mm3/Nm).

The effect of CeF 3 on the mechanical and tribological properties of Ni-based alloy

The Ni-based alloys with various proportions of CeF 3 as lubricant and active element were prepared by hot-pressing and sintering in an intermediate frequency inducing oven. The effects of CeF 3 addition on the tribological and some mechanical properties of the alloy were investigated on a pin-on-disk tribometer. The results indicated that the compressive strength and impact roughness as well as the tribological properties of the alloy were improved by adding 3 wt% CeF 3. It was supposed that CeF 3 can effectively act as an additive, which exhibits beneficial effects on the mechanical and tribological properties of Ni-based alloy.

Effect of copper on the tribological properties of Al-Si base alloys

It is well established that rapid solidification of A1base alloys after processing powders, splats and ribbons through the powder metallurgy route of compaction followed by extrusion results in microstructural improvements, leading to improved properties [1-5]. It has even been possible to attain stability of the improved properties at elevated temperatures by adding intermetaltics, which precipitate out as dispersion strengthened phases [6, 7]. 350 Among the various alloy systems investigated, 325 hypereutectic A1-Si alloys have shown extension of 300 solid solubility beyond equilibrium limits up to the eutectic composition [8, 9] and improvements in 275 properties such as hardness, tensile strength and 25o mechanical properties in the consolidated and ~ 225 extruded product [2, 3, t0]. The A1-Si alloys are g zoo conventionally wear resistant alloys that find applica~ 175 tions as pistons and bearings. This letter reports an attempt to study the ~ 150 tribological properties of rapidly solidified and ~ 125 processed A1-Si base alloys, with and without ternary 1 oo additions. The effect of copper on the tribological 75 properties has been determined using X-ray diffrac5o tion (XRD). Conventional binary A1-Si alloys and alloys with 25 ternary addition of copper were prepared using 0 0 aluminium and solutes of 99.6% and 99.9% purity, (a) respectively. From these, conventionally prepared alloys, in batches of about 1 kg, were remelted at 1123 K in a resistance heating furnace and rapidly solidified to splats at a cooling rate of 105 Ks -1. The 3oo experimental details are given elsewhere [11]. Selected fractions of these splats were consolidated into billets of diameter 76 mm and extruded at 623 K 25o to rods of diameter 19 ram, at an extrusion rate of 16:t. Conventionally cast alloys of the same 2oo compositions were also extruded under the same "~ • g experimental conditions for comparison. The tribological properties of these alloys were _o 450 determined on a standard pin-on-disc set-up, in which cylindrical pins of diameter 8 mm were slid against a polished steel disc of hardness 30RC at loads 100 between 3 and 12 N. The wear rate was calculated from the slope of the steady rate wear region of the plot between weight loss and sliding distance. 5o Wear debris was collected and analysed using XRD for the alloy systems in both the rapidly 0 solidified extruded and conventionally cast extruded o conditions to assess the difference in the wear (b) behaviour. The chemical analyses of the conventionally cast and rapidly solidified alloys are given in Table I. It may be seen that there is no appreciable change in