scholarly journals Effects of Temperature on Wear Properties and Mechanisms of HVOF Sprayed CoCrAlYTa-10%Al2O3 Coatings and H13 Steel

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1224
Author(s):  
Zheng Wei ◽  
Yuping Wu ◽  
Sheng Hong ◽  
Weihua Yang ◽  
Wei Shi
Keyword(s):  
Wear Rate ◽  
Wear Properties ◽  
H13 Steel ◽  
Hvof Spraying ◽  
Different Temperatures ◽  
Effects Of Temperature ◽  
Increasing Temperature ◽  
Worn Surface ◽  
Oxygen Fuel ◽  
Better Than

In this study, the CoCrAlYTa-10%Al2O3 coatings were prepared by the high-velocity oxygen-fuel (HVOF) spraying. A series of ball-on-disk sliding wear tests were conducted to evaluate the tribological properties of the coatings at different temperatures (25 °C, 200 °C, 400 °C, and 600 °C). The results showed that the average coefficients of friction (COFs) of the CoCrAlYTa-10%Al2O3 coatings were lower than that of H13 steel at different temperatures. The average COFs of the CoCrAlYTa-10%Al2O3 coatings and H13 steel both decreased with increasing temperature. The wear rate of the CoCrAlYTa-10%Al2O3 coatings increased first and then decreased. The microhardness of worn surface of the CoCrAlYTa-10%Al2O3 coatings increased with increasing temperature, while the microhardness of worn surface of H13 steel at 25 °C and 200°C was higher than that at 400 °C and 600 °C. The wear mechanism of the two materials was mainly abrasive wear. The tribofilms were formed on the worn surface of the CoCrAlYTa-10%Al2O3 coatings, which had a good protective effect. Due to thermal softening and low binding strength of debris, it was difficult for H13 steel to form the tribofilms. The wear rate of H13 steel was much higher than that of the CoCrAlYTa-10%Al2O3 coatings at 400 °C and 600 °C, indicating that the high temperature wear resistance of the coatings was much better than that of H13 steel.

scholarly journals Preparation and Tribological Properties of Modified MoS2/SiC/Epoxy Composites

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1731
Author(s):  
Cheng Liu ◽  
Meijuan Li ◽  
Qiang Shen ◽  
Haikun Chen
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Resin Matrix ◽  
Wear Properties ◽  
Inorganic Particles ◽  
Volume Wear ◽  
Friction And Wear Properties ◽  
Worn Surface ◽  
Better Than

In order to improve the tribological properties of epoxy (EP), EP composites were prepared by filling different proportions of silicon carbide (SiC) particles and molybdenum disulfide (MoS2) powder. SiC and MoS2 particle surfaces were modified by the silane coupling agent KH560 to improve dispersion and avoid agglomeration of the inorganic particles in the EP resin matrix. The effect of different proportions of modified MoS2 content on the tribological properties of SiC/EP composites, and the wear mechanism of the worn surface, were investigated when the filler content was fixed at 55 wt.%. The results indicate that the friction and wear properties of modified MoS2/SiC/EP composites are better than SiC/EP composites without modified MoS2. When the modified MoS2 content is 4 wt.%, the average friction coefficient and volume wear rate of the modified MoS2/SiC/EP composite are 0.447 and 14.39 × 10−5 mm3/N·m, respectively, which is reduced by 10.06% and 52.13% in comparison with that of the 55 wt.% SiC/EP composite. Furthermore, the average friction coefficient of a composite containing 4 wt.% MoS2 is 16.14% lower, and the volume wear rate is 92.84% lower than that of pure EP.

Study and Optimization of Metal Based Sintered Materials for Automotive Brake Friction Production

2016 ◽  
Vol 254 ◽  
pp. 20-26 ◽  
Author(s):  
Ildiko Peter ◽  
Mario Rosso
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Cost Effective ◽  
Wear Properties ◽  
Electron Microscopies ◽  
High Durability ◽  
Constant Friction ◽  
Different Temperatures ◽  
Materials Used ◽  
Application Optimization

The study aims obtaining materials with a high and constant friction coefficient, a high durability and thermal stability that is associated to a lower wear rate, to the absence of noise during braking and to good self-brazing capacity. Cu and Fe-based friction materials have been sintered and the influence of the loading graphite and ceramic filler powders on the friction and wear properties were investigated. Optimization of the composition and of the sintering method were performed targeting to obtain higher tribological properties, compared to the actually produced polymer matrix materials used for the same purpose, in a cost-effective way. The samples, sintered at different temperatures were observed by optical and scanning electron microscopies, while the tribological behavior was investigated by the evaluation of the friction coefficient and wear rate. The worn surfaces of the wear samples were analyzed: principally an abrasive wear was revealed, explained mostly by the presence of ceramic particles. Moreover, due to the high pressure applied combined to an increased temperature, the presence of adhesive wear was detected. The experimentally achieved results show that using a Cu based material with a moderate graphite and ceramic content is a promising material for the considered application. Optimization of the noise reduction during braking is undergoing.

Influence of Sand Variety on Erosion Wear Properties of Nanostructured WC-12Co Coatings Deposited by HVOF Spraying

2011 ◽  
Vol 396-398 ◽  
pp. 472-477
Author(s):  
Yan Liu ◽  
Li Jun Wang ◽  
Hui Chen ◽  
Ming Jing Tu
Keyword(s):  
Failure Mechanism ◽  
Quartz Sand ◽  
High Velocity ◽  
Working Condition ◽  
High Velocity Oxygen Fuel ◽  
Erosion Wear ◽  
Wear Properties ◽  
Hvof Spraying ◽  
Experiment System ◽  
Oxygen Fuel

Nanostructured WC-12Co coating was prepared by means of High Velocity Oxygen Fuel (HVOF) spraying technology in this research. The erosion wear experiment system was developed to simulate the working condition to study the erosion wear properties. The corundum sand with main composition of Al2O3 and quartz sand with main composition of SiO2 were used to investigate the effects of sand variety on the erosion wear properties. The erosion wear failure mechanism of the coatings was also analyzed. The results show that the failure mechanism of the coating eroded by corundum sand is cracking between WC grains, while for the coating eroded by quartz sand, the failure mechanism is microcutting and microploughing.

scholarly journals The effect of temperature on tacticity for bulk thermal polymerization of styrene

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Farshid Ziaee ◽  
Mehdi Nekoomanesh ◽  
Hamid Salehi Mobarakeh ◽  
Hassan Arabi
Keyword(s):  
Thermal Polymerization ◽  
Effect Of Temperature ◽  
Polymerization Temperature ◽  
Deuterated Chloroform ◽  
Methylene Carbon ◽  
Aromatic Carbon ◽  
First Order ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Better Than

AbstractThree types of polystyrenes were prepared at different temperatures of 50, 150 and 250°C by bulk thermal polymerization of styrene below 20 percent of conversion. The assignment of all stereosequences at pentad level of quaternary aromatic carbon and hexad level of methylene carbon of the polystyrenes were done using 13C Liquid NMR in deuterated chloroform at similar conditions. Bernoullian and first-order Markov statistics were calculated and the results were compared with experimental NMR results. It is shown that first-order Markov statistics fit slightly better than Bernoullian statistics for the assigned carbons. The results indicated that by increasing polymerization temperature the probability of meso addition (Pm) in polystyrene chains was enhanced. Pm was calculated for polystyrenes prepared at 50, 150 and 250°C and corresponding values were 0.378, 0.398 and 0.402 respectively. It was shown that by increasing temperature the polymerization is directed toward the Bernoullian propagation. By increasing the NMR acquisition temperature from 20 to 65°C higher resolution especially in quaternary aromatic carbon was achieved and the related peak was splitted to 16 peaks corresponding to a heptad level compared to 10 peaks in 20°C.

Research on Dynamic Erosion Wear Behavior of HVOF Sprayed Nanostructured WC-12Co Coating

2013 ◽  
Vol 634-638 ◽  
pp. 2997-3001
Author(s):  
Yan Liu ◽  
Hui Chen ◽  
Guo Qing Gou ◽  
Ming Jing Tu
Keyword(s):  
Wear Behavior ◽  
High Hardness ◽  
Layer By Layer ◽  
Erosion Wear ◽  
Wear Properties ◽  
Hvof Spraying ◽  
Simulating Experiment ◽  
Petroleum Chemical ◽  
Erosion Test ◽  
Oxygen Fuel

Erosion wear is an important failure mode existing in hydropowder, petroleum, chemical industry and other fields. Nanostructured WC-Co materials possess excellent erosion wear resistance due to their outstanding combination of high hardness and excellent fracture toughness. Nanostructured WC-12Co coating was prepared by means of High Velocity Oxygen Fuel (HVOF) spraying technology in this research. The simulating experiment system was developed to study the erosion wear properties. The corundum sand with main composition of Al2O3 was used to investigate the dynamic erosion properties of nanostructured WC-12Co coating. The dynamic failure mechanism of the coatings was also analyzed by Scanning Electron Microscope (SEM). The results show that the coating is worn layer by layer in the erosion test. The bonding between the layers and the thickness of the coating should be increased to elongate the coating life.

Friction and wear properties of poly(ether sulfone) containing perfluorocarbon end group

2017 ◽  
Vol 30 (2) ◽  
pp. 247-253 ◽  
Author(s):  
Ye Zhu ◽  
Yingshuang Shang ◽  
Haibo Zhang ◽  
Lianjun Ding ◽  
Yunping Zhao ◽  
...  
Keyword(s):  
Wear Rate ◽  
Photoelectron Spectroscopy ◽  
Tribological Property ◽  
Friction And Wear ◽  
Performance Enhancement ◽  
Wear Test ◽  
Material Surface ◽  
Wear Property ◽  
Wear Properties ◽  
Worn Surface

Poly(ether sulfone) (PES) with high coefficient of friction (COF) and wear rate needs treatment to enhance its tribological property in engineering plastic area. Here, the low surface energy of perfluorocarbon chains terminated poly (ether sulfone) (PES-F) had been used to improve the tribological property of such self-lubricating materials. In this research, the performance enhancement due to the existence of perfluorocarbon group on the material surface was discussed on improvement of anti-friction and wear resistance. On the premise of mechanical strength guarantee, the variation regularity of COF and volume wear rate of PES-F were quantitatively analyzed through the pin-on-disc wear test apparatus, combined with X-ray photoelectron spectroscopy analysis. It was found that PES-F exhibited the best tribological property during the initial phases of friction test, attributing to the highest content of F on the material surface. Observation of PES-F worn surface and wear debris revealed that the COF and wear rate of modified PES were decreased not only due to the effect of perfluorocarbon group but also by the change of worn surface morphology, both of which were the main reasons for anti-friction and anti-wear property enhancement.

Effect of Temperature and Water Immersion on the Mechanical Properties of Coated Fabrics

2010 ◽  
Vol 129-131 ◽  
pp. 230-234
Author(s):  
Ying Ying Zhang ◽  
Qi Lin Zhang ◽  
Chuan Zhi Zhou ◽  
Ying Zhou
Keyword(s):  
Mechanical Properties ◽  
Water Immersion ◽  
Effect Of Temperature ◽  
C 23 ◽  
Different Temperatures ◽  
Temperature Induction ◽  
Effects Of Temperature ◽  
C 50 ◽  
Coated Fabrics ◽  
Increasing Temperature

As composite, the mechanical properties of coated fabrics are sensitive to environment. This paper presented mechanical properties under different environments. A list of uniaxial tests are carried out under different temperatures including -20°C, 0°C, 23°C, 50°C, and 70°C. First, the tensile behaviors at room temperature and the failure behaviors are studied. Then, the effects of temperature on mechanical properties are determined. Finally, the effects of water immersion on mechanical properties are discussed. Results show PTFE coated fabrics remained unchanged in varying temperature and humidity. The temperature has effects on the mechanical properties of PVC coated fabrics. With increasing temperature, the strength decrease and the strain at break increase. The temperature induction factors are proposed for the design and analysis. The water immersion has little effect on the mechanical properties because of the impervious coating.

Wear Behaviors of MoSi2 at Elevated Temperatures

2008 ◽  
Vol 368-372 ◽  
pp. 961-963
Author(s):  
Hou An Zhang ◽  
Xiao Pin Hu ◽  
Wei Cheng Tan ◽  
Cun Shi
Keyword(s):  
Wear Rate ◽  
Friction And Wear ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Vacuum Furnace ◽  
Wear Properties ◽  
Brittle Transition ◽  
Deformation And Fracture ◽  
Friction And Wear Properties ◽  
Worn Surface

MoSi2 was prepared by SHS, and then pressed under 300 MPa at room temperature and sintered at 1600 °C for 1 h in a vacuum furnace. The tribological properties of MoSi2 against Al2O3 in the temperature range from 700°C to 1100 °C were investigated. Microphotographs and phases of the worn surface of MoSi2 were observed by SEM and XRD. Results showed that MoSi2 has well friction and wear properties below 900 °C. When temperature rises from 900 °C to 1000 °C, wear rate of MoSi2 is raised by 20.8% which is attribute to the change of wear mechanism. The main wear mechanisms of MoSi2 are adhesion and oxidation at high temperatures. When over 900 °C, because of ductile - brittle transition characteristic of this material, plastic deformation and fracture are also found on the worn surface of MoSi2. This leads to the high wear rate of MoSi2.

scholarly journals The Effects of Temperature and of Egg-Laying on the Longevity of Drosophila subobscura

2002 ◽  
Vol 2002 (37) ◽  
Author(s):  
J. Maynard Smith
Keyword(s):  
Animal Species ◽  
Initial Period ◽  
Egg Laying ◽  
Drosophila Subobscura ◽  
Force Of Mortality ◽  
Different Temperatures ◽  
Effects Of Temperature ◽  
Favourable Environment ◽  
Rate Of Ageing ◽  
Increasing Temperature

If an outbred population of adult Drosophila is kept from the time of emergence in a uniform and favourable environment there is a fairly protracted initial period during which very few individuals die, followed by a period during which the force of mortality rises rapidly until all individuals are dead. Similar life tables can be obtained for most animal species, provided that the environment is favourable and the population is neither genetically very diverse nor excessively inbred. Such results show that progressive changes take place in individuals, starting at the time of emergence, and that these changes ultimately result in death or render individuals increasingly susceptible to various extrinsic causes of death. As would be expected, in poikilotherms such changes proceed more rapidly at higher temperatures, as is shown by the decrease in the expectation of life with increasing temperature. It was the purpose of the present investigation to discover how far the processes responsible for death in D. subobscura are the same at different temperatures, differing only in the rate at which they proceed, and how far different processes are concerned at different temperatures. The results obtained strongly suggest that different processes are responsible for ageing at different temperatures; they also indicate a connexion between the rate of egg-laying and the rate of ageing, and this possibility has been confirmed by a study of ageing in virgin females and in females lacking ovaries. Reproduced by permission. J. Maynard Smith, The Effects of Temperature and of Egg-Laying on the Longevity of Drosophila subobscura. J. Exp. Biol. 35 , 832-842 (1958).

Tribological Performance of Translucent Dy-α-Sialon Ceramics

2008 ◽  
Vol 403 ◽  
pp. 115-116
Author(s):  
Qian Liu ◽  
Lin Hua Gui ◽  
Jun Hu Meng ◽  
Zhi Feng Li
Keyword(s):  
Wear Resistance ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Applied Load ◽  
Tribological Performance ◽  
Wear Properties ◽  
Wear Resistant ◽  
Effects Of Temperature

A considerable test was made to figure out the effects of temperature and sliding conditions on the wear properties of the translucent Dy--Sialon. The friction coefficient was 0.54 at RT, 0.26 at 100 oC, and 0.81 at 600 oC respectively under an applied load of 5N. The wear rate was 6.91×10-15 at RT and 1.0×10-15 at 100 oC for the same Dy--Sialon sample. Obviously Dy-Sialon shows an excellent wear resistance under a suitable sliding condition, a load of 5N and at 100 oC. This appears attractive and important for Dy-Sialon ceramics to be used as a type of special wear resistant materials, with an optical translucence.

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