Influences of work hardening and crystallographic texture on dry-sliding tribological properties of friction stir processed pure Ti with slow rotation speed

The article presents the results of tests of the tribological properties of a bearing alloy on a tin matrix (B89) after surface modification by means of friction stir processing (FSP) with a Whorl tool. The samples were processed using two tool speeds of 280 and 580 RPM and a constant linear speed of 355 mm/min. The obtained results proved the significant influence of FSP on both the morphology of the precipitates and the investigated properties. Changes in the nature and course of friction were also observed, including the participation of individual wear mechanisms in the studied test conditions. The use of the 560 RPM tool rotation speed reduces the friction coefficient and the weight loss by about 30%. The flexural strength was also increased from 123 to 307 MPa.

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An appraisal of characteristic mechanical properties and microstructure of friction stir welding for Aluminium 6061 alloy – Silicon Carbide (SiCp) metal matrix composite

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.13.4.2019.07.0463 ◽

2019 ◽

Vol 13 (4) ◽

pp. 5804-5817

Author(s):

Ibrahim Sabry

Keyword(s):

Tensile Strength ◽

Ultimate Tensile Strength ◽

Metal Matrix Composite ◽

Matrix Composite ◽

Metal Matrix ◽

Welded Joint ◽

Rotation Speed ◽

Fusion Welding ◽

Friction Stir ◽

Al 6061

It is expected that the demand for Metal Matrix Composite (MMCs) will increase in these applications in the aerospace and automotive industries sectors, strengthened AMC has different advantages over monolithic aluminium alloy as it has characteristics between matrix metal and reinforcement particles. However, adequate joining technique, which is important for structural materials, has not been established for (MMCs) yet. Conventional fusion welding is difficult because of the irregular redistribution or reinforcement particles. Also, the reaction between reinforcement particles and aluminium matrix as weld defects such as porosity in the fusion zone make fusion welding more difficult. The aim of this work was to show friction stir welding (FSW) feasibility for entering Al 6061/5 to Al 6061/18 wt. % SiCp composites has been produced by using stir casting technique. SiCp is added as reinforcement in to Aluminium alloy (Al 6061) for preparing metal matrix composite. This method is less expensive and very effective. Different rotational speeds,1000 and 1800 rpm and traverse speed 10 mm \ min was examined. Specimen composite plates having thick 10 mm were FS welded successfully. A high-speed steel (HSS) cylindrical instrument with conical pin form was used for FSW. The outcome revealed that the ultimate tensile strength of the welded joint (Al 6061/18 wt. %) was 195 MPa at rotation speed 1800 rpm, the outcome revealed that the ultimate tensile strength of the welded joint (Al 6061/18 wt.%) was 165 MPa at rotation speed 1000 rpm, that was very near to the composite matrix as-cast strength. The research of microstructure showed the reason for increased joint strength and microhardness. The microstructural study showed the reason (4 %) for higher joint strength and microhardness. due to Significant of SiCp close to the boundary of the dynamically recrystallized and thermo mechanically affected zone (TMAZ) was observed through rotation speed 1800 rpm. The friction stir welded ultimate tensile strength Decreases as the volume fraction increases of SiCp (18 wt.%).

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Deposition and Tribological Properties of CVD Diamond/Diamond-Like Carbon Composite Films

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.565.615 ◽

2012 ◽

Vol 565 ◽

pp. 615-620

Author(s):

Bin Shen ◽

Liang Wang ◽

Su Lin Chen ◽

Fang Hong Sun

Keyword(s):

Surface Morphology ◽

Composite Film ◽

Tribological Properties ◽

Composite Films ◽

Cvd Diamond ◽

Carbon Composite ◽

Dry Sliding ◽

Diamond Like Carbon ◽

Dlc Film ◽

Bonding State

The CVD diamond/diamond-like carbon composite film is fabricated on the WC-Co substrate by depositing a layer of Diamond-like Carbon film on the surface of conventional Micro- or Nano-crystalline diamond film. The hot filament chemical vapor deposition (HFCVD) method and vacuum arc discharge with a graphite cathode are adopted respectively to deposit the MCD/NCD and DLC films. A variety of characterization techniques, including filed emission scanning electron microscope (FE-SEM) and Raman spectroscopy are employed to investigate the surface morphology and atomic bonding state of as-deposited MCD/DLC and NCD/DLC composite film. The results show that both MCD/DLC and NCD/DLC composite films present similar surface morphology with the MCD and NCD films, except for scattering a considerable amount of small-sized diamond crystallites among the grain boundary area. The atomic-bonding state of as-deposited MCD/DLC and NCD/DLC composite films is determined by the top-layered DLC film, which is mainly consisted of amorphous carbon phase and no discernible sp3 characteristic peak can be observed from their Raman spectrum. Furthermore, the tribological properties of as-deposited MCD/DLC and NCD/DLC composite films is examined using a ball-on-plate reciprocating friction tester under both dry sliding and water-lubricating conditions, comparing with conventional DLC, MCD and NCD films. Silicon nitride balls are used as counterpart materials. For the CVD diamond/DLC composite films, the self-lubricating effect of top-layered DLC film is beneficial for suppressing the initial friction peak, as well as shortening the run-in period. The average friction coefficients of MCD/DLC and NCD/DLC composite films during stable sliding period are 0.07 and 0.10 respectively in dry sliding; while under water-lubricating condition, they further decreases to 0.03 and 0.07.

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Tribological Properties of Polytetrafluoroethylene Improved by Incorporation of Fluorinated Graphene with Various Fluorine/Carbon Ratios Under Dry Sliding Condition

Tribology Letters ◽

10.1007/s11249-020-01398-3 ◽

2021 ◽

Vol 69 (1) ◽

Author(s):

Lifen Liang ◽

Laizhou Song ◽

Yulin Yang ◽

Fei Li ◽

Yalong Ma

Keyword(s):

Tribological Properties ◽

Dry Sliding ◽

Fluorinated Graphene

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Study of friction stir spot welding for thermotolerant engineering thermoplastic polyimide joints

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405421995619 ◽

2021 ◽

pp. 095440542199561

Author(s):

Jicheng Gao ◽

Jiachen Dong ◽

Sunyi Zhang ◽

Liang Yu ◽

Huiming Jin ◽

...

Keyword(s):

Shear Strength ◽

Spot Welding ◽

Dwell Time ◽

Rotation Speed ◽

Mixing Time ◽

Friction Stir Spot Welding ◽

Scanning Calorimetry ◽

Friction Stir ◽

Base Materials ◽

Engineering Plastics

In this research, thermoplastic polyimide (TPI) were welding via friction stir spot welding (FSSW) in order to evaluate the feasibility of the technology. The welding tool with a tri-flute pin was used for keeping the welding effectiveness. The effect of the rotation speed and dwell time on the microstructure and shear strength was studied. The results shows that the number of gap defects between the shoulder affect zone and the pin affect zone decreased with the increase of the rotation speed. The boundary of the shoulder affect zone and the pin affect zone was no clear when increasing the dwell time from 10 s to 20 s. Long dwell time could increase the mixing time and reduce the materials viscosity, which made the structure was denser. The maximal shear strength was obtained 85.5% of the base materials. The differential scanning calorimetry (DSC) results indicated that the melting behaviour of different regions was no obvious difference. It indicated that FSSW had a feasible and potential technology to join the high temperature resistant engineering plastics.

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Effect of Stirring Pin Rotation Speed on Microstructure and Mechanical Properties of 2A14-T4 Alloy T-Joints Produced by Stationary Shoulder Friction Stir Welding

Materials ◽

10.3390/ma14081938 ◽

2021 ◽

Vol 14 (8) ◽

pp. 1938

Author(s):

Haifeng Yang ◽

Hongyun Zhao ◽

Xinxin Xu ◽

Li Zhou ◽

Huihui Zhao ◽

...

Keyword(s):

Mechanical Properties ◽

Friction Stir Welding ◽

Rotation Speed ◽

Weld Nugget ◽

Al Alloy ◽

Nugget Zone ◽

T Joints ◽

Friction Stir ◽

Stationary Shoulder ◽

Microstructure And Mechanical Properties

In this study, 2A14-T4 Al-alloy T-joints were prepared via stationary shoulder friction stir welding (SSFSW) technology where the stirring pin’s rotation speed was set as different values. In combination with the numerical simulation results, the macro-forming, microstructure, and mechanical properties of the joints under different welding conditions were analyzed. The results show that the thermal cycle curves in the SSFSW process are featured by a steep climb and slow decreasing variation trends. As the stirring pin’s rotation speed increased, the grooves on the weld surface became more obvious. The base and rib plates exhibit W- or N-shaped hardness distribution patterns. The hardness of the weld nugget zone (WNZ) was high but was lower than that of the base material. The second weld’s annealing effect contributed to the precipitation and coarsening of the precipitated phase in the first weld nugget zone (WNZ1). The hardness of the heat affect zone (HAZ) in the vicinity of the thermo-mechanically affected zone (TMAZ) dropped to the minimum. As the stirring pin's rotation speed increased, the tensile strengths of the base and rib plates first increased and then dropped. The base and rib plates exhibited ductile and brittle/ductile fracture patterns, respectively.

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