Showing papers on "Spray forming published in 2021"

Performance Enhancing of Spray Formed Al/Graphite Alloy Composite by Rolling

Abstract: The present study outlines the effect of warm rolling on the Al/Graphite alloy composite to investigate its effect on mechanical performance. The Al/Graphite alloy composite has been fabricated by the spray forming process and has been subjected to the rolling at 250 °C with varying reduction. The rolled composite has been studied under different characterization techniques such as X-ray fluorescence (XRF), optical microscopy, scanning electron microscopy with energy dispersive spectroscopy (EDS) and tensile tester. The XRF and EDS results indicate that the Al/Graphite alloy composite is successfully formed. The microscopy results show that the grain size of α-aluminium and agglomeration of the particles refine by rolling and they continuously decrease with an increase in rolling reduction. The strength and percentage elongation of the composite improves by rolling and they continuously increase with an increase in rolling reduction. Further, the fracture surface study has also been performed and it indicates that the fracture of the composite alters from brittle to ductile mode with an increase in rolling reduction. The appeared fracture surface of the composite has also been correlated with the produced microstructure and the tensile properties.

Metallurgical Characteristics, Compressive Strength, and Chemical Degradation Behavior of Aluminum-Cenosphere Composite Foam Developed by Spray Forming Route

Abstract: In the present study, the microstructural characteristics, compressive strength, and corrosion behavior of aluminum-cenosphere composite foam (CF) developed by spray forming route (processed with 5 Psi (3.45 × 104 N/m2) and 10 Psi (6.90 × 104 N/m2) hydrogen pressure) has been undertaken. The microstructure of the spray-formed coupon consists of hollow cenosphere particles distributed uniformly in aluminum matrix. Compressive yield strength (YS) of the aluminum-cenosphere foam (CF) is different from commercially pure aluminum (cp-Al). It is found that the YS of the foam processed with 5 Psi is 83.62 MPa and for the foam processed at 10 Psi is 113.32 MPa as compared to 104.42 MPa for cp-Al. A detailed study of corrosion behavior through electrochemical measurements indicates that CF exhibits a reduced corrosion rate from 0.092 (for cp-Al) to 0.056 mm/year and 0.080 mm/year for the samples processed with 10 and 5 Psi, respectively. Through a detailed analysis of Nyquist and Bode plots derived from EIS measurements, it is concluded that mostly localized corrosion occurs in all the samples. The post-corrosion microstructural study confirms that interface of aluminum and cenosphere is the potential area for initiation of corrosion.

Enhancing the Microstructure and Tribological Performance of Spray Formed Al Alloy by Cryorolling

Abstract: In the present study, the microstructure and tribological performance of Al alloy has been enhanced by cryorolling. The Al-6 wt.% Si alloy has been selected as Al alloy which has been prepared by spray forming technique with 400 mm flight distance. Developed spray formed Al alloy has been subjected to cryorolling with different thickness reduction (25% and 50%) on non-reversing rolling mill using liquid nitrogen. The alteration in microstructure and tribological properties has been studied by different techniques. The microstructure results indicate that the cryorolling process refines the size of aluminium rich phase and silicon particles of spray formed Al alloy. The tribological testing results illustrate that the wear rate of Al alloy decrease by cryorolling. While the cumulative volume loss and wear rate increase with an increasing sliding distance and applied load for spray formed and cryorolled Al alloy. The coefficient of friction exhibits a fluctuating action with sliding distance while it decreases with an applied load and cryorolling. The worn surfaces have also been analyzed under scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM) techniques to study the operative wear mechanisms. Hardness property and microscopic analysis of Al alloy have also been correlated with tribological properties.

Experimental Study of Liquid Spray Mode of Twin Fluid Atomizer Using Optical Diagnostic Tool

Abstract: Twin fluid atomizers allow for two different spray forming modes, flow focusing and flow blurring, depending on the operating, geometric, and thermophysical properties of the working liquids. In flow focusing mode, the liquid jet breaks outside the injector, whereas in flow blurring mode, the liquid jet breaks inside the atomizer. Operating conditions are believed to play an essential role in determining the size and velocity of droplets with specific geometric and fluid properties. This work investigates the effect of air flow rate and liquid flow rate on spray characteristics by varying them independently. The geometric parameters, height (H = 0.3 mm) and orifice diameter (D = 1.5 mm) of the atomizer are kept constant (with H/D = 0.2). Spray mode is identified using high-speed images. Phase Doppler particle analyzer is used to measure droplet size and velocity simultaneously. Regardless of liquid flow rate, flow focusing mode is observed at low air flow rate and flow blurring mode is observed at high air flow rate. In general, flow blurring mode produced smaller droplets at higher velocities than flow focusing mode. The Joint probability distribution function of droplet size and velocity shows unimodal near the exit of the atomizer and bimodal distribution around 50 mm downstream due to the completion of the secondary breakup around that position and the subsequent loss of momentum due to the resistance of the surrounding air from the injector outlet. Flow focusing mode showed that sauter mean diameter and mass median diameter tend to increase initially due to coalescence of the spray and begin to decrease due to secondary breakup. The joint probability distribution of droplet Weber number and the droplet Reynolds number indicate that the flow blurring spray produced finer and faster droplets than the flow focusing spray. Overlapping of two Gaussians representing smaller and larger droplets best fits the droplet probability distribution as compared to lognormal or gamma or beta distribution.

Effect of zirconium oxide particulate composites with Al-Si on the microstructural and mechanical properties of hot pressed, spray forming and stir casting methods

Abstract: This research work aims to investigate the aluminum and silicon alloy reinforced with the ZrO2 powder particles, which has been fabricated using stir casting and spray deposition method. The mechan...

Influence of Cryorolling on Spray-Formed Al–Si Alloy

Abstract: In the present study, the influence of the secondary process, namely cryorolling on microstructure, porosity and hardness of spray-formed Al–Si alloy has been studied. The Al–Si alloys included of 6 wt% of Si have been selected and have been made by the spray forming technique using nitrogen as atomized gas. Further, cryorolling of spray-formed Al–Si alloy has been performed with a different reduction on a rolling mill. The cryorolled spray-formed Al alloy with different reductions has been characterized by different techniques. The X-ray diffractometer (XRD) analysis indicates that the alloy is Al–Si alloy, and no other phases are present. However, microstructure studies indicate that the spray-formed Al–Si alloy consists of equiaxed grains of α-aluminium and Si particles, which refine by cryorolling. The porosity measurement indicates that the value of porosity decreases continuously with an increasing thickness reduction under cryorolling. The hardness has correlated with the porosity and the evolved microstructure of the Al alloy. The 50% cryorolled spray-formed Al–Si alloy exhibits the maximum improvement in properties.

Correlation between microstructural and corrosion resistance of boron-modified duplex stainless steel processed by spray-forming

Abstract: In this work was investigated the duplex stainless steel modified by boron by spray-forming, in order to characterize the using different techniques, optical microscopy, SEM-FEG, X-ray diffraction, Rama spectroscopy and hardness (VH) and Thermo-Calc software, with goal of determining the corrosion resistance. The corrosion resistance test was performed in aerated solution of 0.1 M, immersed in different aggressive media electrolytes, alkaline and acidic mediums. As result through the EDS technique was verified that in the phase the Cr element predominates, but in the phase the Fe and Ni elements prevail. XRD spectra shown different meta-stable phases and mainly the (FeCr)2B phase, the percentage of the and phases are similar. Besides, the measurement was around 460 HV. Furthermore, impedance plots at different electrolytes had linear behavior, which their polarization resistances are extremely high in all solutions. However, the potential of corrosion whose magnitude is small, also the rates were close to zero. Consequently, the corrosion resistance in all studied solutions were extremely high and it can be attributed due to presence of the (FeCr)2B phase, meta-stables phases and similar proportion of the three phases present. This alloy can be successfully used in the chemical, oil and gas industries and petrochemical process plants.

Microstructure and Porosity Behavior of Spray Formed Al Alloy Processed by Cold Rolling

Abstract: An efficient spray forming technique was utilized to cast Pb-added Al-Si alloys. It was then rolled to a different percentages (0–80%) using rolling machine and microstructural characteristics as well as porosity behavior of casting alloy were systematically studied. It is noteworthy that the distribution of Pb was nearly uniform all through the aluminum phase and it was mainly at the grain boundary. Also, the grains of aluminum were found to be elongated along the rolling direction after 80% rolling. Porosity was minimum at peripheral region of the deposit and it decreased as rolling percentage is increased.

Method for manufacturing sensor by means of printing

Abstract: Disclosed is a method for printing a sensor, the method comprising the following steps: step S1, spreading first powder in a forming cylinder (130) of a binder spray forming device (100), and carrying out binder spray printing from bottom to top according to a sensor model so as to form a sensor shell (20) having a first accommodating space in the middle of a top opening, and an accommodating cavity (22) provided in the sensor shell (20); step S2, spreading second powder in the forming cylinder (130) of the binder spray forming device (100), and carrying out binder spray printing from bottom to top according to the sensor model, so as to form a sensor (24); step S3, lifting up the accommodating cavity (22) from bottom to top, and recovering the first powder in the accommodating cavity (22); step S4, putting the sensor (24) in the sensor shell (20), and removing the binder from the sensor (24) and the sensor shell (20); and step S5, sintering the sensor (24) and the sensor shell (20) so as to form a sensor element (200, 300). The method for printing a sensor is lower in cost and higher in efficiency.