مجله مهندسی ساخت و تولید ایران
سال هفتم شماره 9 (آذر 1399)

Nanoparticle manipulation is a process from the branch of nanotechnology, which is performed on the basis of atomic force microscopy. Today, due to the high importance of industry prosperity and the production of fine-scale equipment, machinery and tools, nanoparticle / micro-particle manipulation is increasingly being used by artisans. In the first phase of this process, the critical force and time are the most basic output factors. Two types of factors include environmental and dimensional factors in determining their fate. In this paper, quantitative and qualitative effects of environmental and dimensional input factors including seven tip radius input, Poisson tip coefficient, tip modulus of elasticity, cantilever height, cantileverlength, cantilever height, cantileverheight And the width of the pole on the four outputs of the critical force between the tip and the particle, the critical time between the tip and the particle, the critical force between the particle and the base plate, and the critical time between the particle and the base plate. The type of qualitative relationship is obtained by either directly or inverting each of the parameters and the amount of variance on the output factors. In quantitative effect, the maximum effect of each parameter is calculated separately. The thickness of the cantilever was the most effective input parameter on the particle-tip and particle-plate critical forces with 75% and 66%, respectively. For critical particle-tip time, the tip radius was the most effective input parameter with 46%, but the cantileverthickness had the most influence on the particle-plate critical time of 81%

This paper has focused on the joint type effect on the creation and gradient temperature of weld metal in the welded pipe. The main purpose is to reduce the heat generated in the weld metal and the temperature gradient in the pipe thickness direction, by joint type Changes. To obtain a suitable joint type, different joint types have been studied experimentally and numerically by Comsol software. By using destructive and non-destructive tests, the mechanical properties, such as the ultimate tensile strength and the elongation of the weld metal, have been investigated. Evaluation of the metallurgical properties, for instance, the grain boundary and the enlargement of the heat affected zone, has also been examined. The results show that changing the joint type reduces the generated temperature 19% and the temperature gradient in the weld metal. Follow it, the grain boundaries increase and a rectangular weld metal profile is created. Increases the ultimate tensile strength 5% but not obvious change in elongation.increases the ultimate tensile strength by 5%.

In this study the radial-forwad-backward extrusion of axially joint cup shaped AM60 magnesium alloy part is investigatd. In the experimental tests, the cylindrical AM60 alloy samples were prepaed and pressed by a punch into the die cavity. In the next step, the initial and extruded samples were investigated in terms of microstructural evolution and mechanical poperties variation. The microscopic observations showed the significant grain refinement of AM60 is occurred at the end of extrusion proessingwhere the fine grains in size of ~7μm are obtained from the initial value of ~75μm. Also, the Vickers microhardness is increased to 88Hv from the initial value of 56 Hv. The obtained results of uni-axial tensile tests showed the increase in yield and ultimate tensile strength to 142.6 and 290.3 from the initial value of 93 and 230MPa, respectively. The extruded sample elongation is incresead to 13.4% from 10% due to texture evolution, grain refinement and breakage of brittle eutectic phases. The macro and micromechancal based cellular automaton (CA) finite element method were implemented to simulate the process to predict the microstructure evolution of AM60 during extrusion processing. The cellular automaton finite element(CAFÉ) and experimentally obtained results were in good agreement. The effect of some important parameters including friction coefficient, gap thickness and height and die corner radius are studied on the variation of maximum forming load, microhardness values and grain size.

Fused Deposition Modeling (FDM) is one of the advanced Additive Manufacturing (AM) techniques that enables the production of complex geometric components from thermoplastic materials. The use of the FDM process in the production of composite parts reduces the production cycle time and manufacturing costs. Since the properties of components fabricated by this method depend on the process parameters, investigating of process parameters and their various effects on the properties of manufactured parts are so necessary. In the present study, the effect of two process parameters including printing pattern and infill density on flexural properties, flexural strength-to-weight, and flexural strength-to-time ratios of FDM fabricated parts have been studied. The investigation is carried out on carbon fiber reinforced Polylactic acid (SCF/PLA) composite. The results indicated that the infill density compared to the printing pattern had a more significant effect on the flexural strength, weight, and build time of fabricated parts. However, considering the flexural strength-to-weight ratio, which is an important factor in the production of the composite parts as a desirable output, the printing pattern plays a more important role than the infill density.

The functional graded Al/Al-Cu-Cr composite was developed by horizontal centrifugal casting method and the effect of mold speed on the microstructure and hardness was investigated. The microstructure assessment and identification of the resulting phases was performed using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) equipped with an Energy Dispersive X-Ray Spectroscopy (EDS). The results showed that ternary in-situ Al/Al-Cu-Cr composite microstructure was consisted of four phases α-Al, Al2Cu, θCr(Al7Cr) and ζ-Al-Cr-Cu. The centrifugal force caused the separation and movement of the intermetallic particles containing chromium (θCr(Al7Cr) and ζ-Al-Cr-Cu) toward the outer region of the composites with a decreasing trend to the middle region. The Al2Cu particles distributed toward the inner region of the specimens and were evenly distributed from the inner region to the middle region. As the mold rotation speed increased, the observed separation gradient increased so that the maximum area fraction of intermetallic particles in the outer region increased from 17% at 600 rpm to 36% at 1800 rpm. The results showed that the in-situ Al/Al-Cu-Cr composite has a higher hardness than the binary Al/Al-Cr composite at the same conditions. So that an increment of 80 percent in hardness was observed for the Al/Al-Cu-Cr composite compared to the Al/Al-Cr composite in their outermost region. As the rotational speed increased from 600 to 1800 rpm, the maximum amount of hardness which was associated with the outermost region of the centrifugally cast Al/Al-Cu-Cr composite increased from 51 to 76 Brinell.

In this research, electroless nanocomposite coating of Ni-P-SiO2-MoS2 and effect of SiO2 and MoS2 nanoparticles on microstructure and wear resistance of coating were investigated. First of all, samples from MO40 (AISI 4140) steel sheet were prepared and coated in Nickel-Phosphorous electroless bath containing 7 g/l SiO2 and MoS2 particles in 90°C and 6.4 pH for 60 minutes. Then, pin on disk wear test was performed to evaluate the wear resistance of the coated and uncoated samples. Several experiments used to explore tribological features of deposited electroless coatings. Field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) images were taken to investigate coating microstructure and its elements, respectively. Microstructural results showed that a uniform coating on substrate was successfully composed. Also, several mechanisms observed during the abrasion process. Abrasive and adhesive mechanisms were active in uncoated samples, but by applying SiO2 and MoS2 nanoparticles, the sliding mechanism was activated. Furthermore, with decreasing friction coefficient, wear resistance increased by 79.3% and also the tribological properties of the sample improved.