A method to rapidly determine the sintering process parameters of powder metallurgy by real-time resistivity monitoring

2016 ◽  
Vol 3 (10) ◽  
pp. 106504 ◽  
Author(s):  
Zhen Xiao ◽  
Huanchao Liu ◽  
Haoran Geng ◽  
Jinfeng Leng
Keyword(s):  
Powder Metallurgy ◽  
Real Time ◽  
Process Parameters ◽  
Sintering Process

Real-time observation of cathodic cleaning during variable-polarity gas tungsten arc welding of aluminium alloy

2009 ◽  
Vol 223 (9) ◽  
pp. 1143-1157 ◽  
Author(s):  
R Sarrafi ◽  
D Lin ◽  
R Kovacevic
Keyword(s):  
Real Time ◽  
Process Parameters ◽  
Arc Welding ◽  
Molten Pool ◽  
Gas Tungsten Arc Welding ◽  
Process Conditions ◽  
Current Electrode ◽  
Gas Tungsten Arc ◽  
Variable Polarity ◽  
Gas Tungsten

Online observation is expected to provide a better understanding of the cathodic cleaning of oxides from the molten pool during variable-polarity gas tungsten arc welding (VP GTAW) of aluminium alloys. In this paper, a machine-vision system with appropriate illumination and filtering is used to monitor in real time the effect of different process parameters on the cleaning of oxides from the molten pool during VP GTAW of Al 6061. Based on the observations, the process conditions under which a clean molten pool can be achieved are determined. In addition, the control of the welding process to maintain the consistency of cathodic cleaning is discussed. The results showed that in order to have an oxide-free molten pool, the solid surface in front of the molten pool should be cleaned from oxides by the electric arc. The choice of process parameters to satisfy this condition has been discussed. It was found that the percentage of direct current electrode positive (DCEP) polarity in the cycle of current has the highest impact on the cathodic cleaning, with the arc current having less influence, and the welding speed showing the least effect. Furthermore, in order to keep the consistency of oxide cleaning, process parameters should be set or controlled to maintain the cleaned zone larger than the molten pool.

scholarly journals EBSD Analysis of Metal Matrix Nanocomposite Microstructure Produced by Powder Metallurgy

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 878 ◽  
Author(s):  
Íris Carneiro ◽  
Filomena Viana ◽  
Manuel F. Vieira ◽  
José V. Fernandes ◽  
Sónia Simões
Keyword(s):  
Powder Metallurgy ◽  
Advanced Materials ◽  
Sintering Process ◽  
Electron Backscattered Diffraction ◽  
Matrix Microstructure ◽  
Metal Matrix Nanocomposite ◽  
The Matrix ◽  
Dislocation Annihilation ◽  
Metal Nanocomposites ◽  
Matrix Nanocomposite

The development of metal nanocomposites reinforced by carbon nanotubes (CNTs) remains a focus of the scientific community due to the growing need to produce lightweight advanced materials with unique mechanical properties. However, for the successful production of these nanocomposites, there is a need to consolidate knowledge about how reinforcement influences the matrix microstructure and which are the strengthening mechanisms promoting the best properties. In this context, this investigation focuses on the study of the reinforcement effect on the microstructure of an Ni-CNT nanocomposites produced by powder metallurgy. The microstructural evolution was analysed by electron backscattered diffraction (EBSD). The EBSD results revealed that the dispersion/mixing and pressing processes induce plastic deformation in the as-received powders. The dislocation structures produced in those initial steps are partially eliminated in the sintering process due to the activation of recovery and recrystallization mechanisms. However, the presence of CNTs in the matrix has a significant effect on the dislocation annihilation, thus reducing the recovery of the dislocation structures.

Effect of process parameters on temperature and force distribution during friction stir welding of armor-marine grade aluminum alloy

2020 ◽  
Vol 235 (1-2) ◽  
pp. 144-154 ◽  
Author(s):  
Shubham Verma ◽  
Joy Prakash Misra
Keyword(s):  
Friction Stir Welding ◽  
Real Time ◽  
Process Parameters ◽  
Tilt Angle ◽  
Welding Speed ◽  
Low Cost ◽  
Maximum Force ◽  
Maximum Temperature ◽  
Force Distribution ◽  
Friction Stir

This research investigates the effect of process parameters on real-time temperature and forces distribution during friction stir welding of AA7039. Experiments are conducted at different rotational speed, welding speed, and tilt angle conditions. For the experimentation, a low-cost real-time force-measuring fixture is indigenously developed in-house. However, eight K-type L-shaped thermocouples are used to examine the real-time temperature distribution. The forces in the z-direction are of a higher magnitude than the x-direction. The maximum force in the z-direction of 3.25 kN is witnessed for 2° tilt angle and a minimum of 2.1 kN for 26 mm/min of welding speed. The maximum force in the x-direction of 0.97 kN is obtained at 2° tilt angle and a minimum of 0.27 kN is obtained at 1.3° tilt angle. The maximum temperature of 390 °C is observed at 1812 r/min, whereas a minimum of 283 °C is observed at 43 mm/min of welding speed. The variations in temperature and force distribution during friction stir welding are also evaluated by utilizing two phenomenological models.

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