Suitable Process Parameters Research Articles

Overview of Adhesive Bonding Technology for Nano- and Microsystem Technics

The review focuses on adhesive bonding technology, which is used both for manufacturing various micro- and nanoelectronic devices, sensors and microsystems, and for assembling or integrating various components. Information on the theory of adhesive bonding mechanisms is presented. The properties and applications of four classes of polymers are reviewed: thermoplastic, ther-mosetting, elastomeric, and hybrid. The classification of different mechanisms used to initialize the curing process of adhesives is presented. Existing methods of applying polymers to the wafer surface are described. The main types of designs and principles of operation of adhesive wafer bonding equipment are presented, as well as its main suppliers. Examples of procedures and suitable process parameters are given for both wafer bonding with a continuous layer of adhesive and wafer bonding with patterned adhesive layers (also called selective or local bonding). The conditions required to improve the quality of the adhesive bond and to reduce the density of defects are specified, including cases of bonding wafers made from different materials. Adhesive wafer bonding is used for the fabrication of three-dimensional integrated circuits, and for the integration of integrated circuits with microsystems such as infrared focal plane arrays, spatial light modulators (micromirror arrays), microtip arrays for data storage systems, and laser systems. Adhesive wafer bonding is also used for the fabrication of microcavities in packaging applications, for manufacturing of liquid crystal on silicon (LcoS) components, for thin-film solar cells, for radiofrequency components, for microfuel cells, for hard disk drive microactuators, for the bioMEMS and micrototal analysis systems.

On failure analysis of three-dimensional printed functionally graded material prepared by direct metal laser sintering

In the past decade, some studies were reported on the successful three-dimensional printing of meta-structure-inspired functionally graded material with two different alloys (having a wide difference in melting range ≈ 450–500 °C) by direct metal laser sintering. But hitherto little has been reported on failure analysis of such meta-structure-inspired three-dimensional printed functional prototypes of dual alloys (17-4 precipitate hardened (PH) stainless steel (SS) and Ti-6Al-4V) with direct metal laser sintering (while fabrication). This study reports the failure analysis of meta-structure inspired dual alloys printing (as FGM) at different processing parameters of direct metal laser sintering. Initially, a pilot study was performed in which a solid structure of Ti-6Al-4V and 17-4 PH SS was successfully printed by selecting the suitable direct metal laser sintering process parameters as functionally graded material (stage 0). In the next stage, specimens of dual alloys were printed with dodecahedron and octet meta-structure of Ti-6Al-4V as a sandwich between the 17-4 PH SS and Ti-6Al-4V layers (stage 1). It has been observed that the octet-based specimen was successfully printed, while the dodecahedron-based sample failed after attaining some height. After successfully octet meta-structure printing of dual alloys (Ti-6Al-4V and 17-4 PH SS), direct metal laser sintering process parameters were further explored for optimization (stage 2). For failure analysis, the specimens with octet meta-structure were fabricated by fixing energy density (in stage 3), hatching distance (in stage 4), laser power (in stage 5), and energy density, hatching distance, laser power, scanning speed (in stage 6). Finally, for confirmation (stage 7), a single specimen was successfully printed by taking process parameters of the successful octet-based sample of stage 2. All the printing failures as per porosity analysis (such as balling phenomenon, caves, and cervices formation) concerning the number of sintered layers in this study are supported with photomicrographic analysis (based on scanning electron microscopy images).

Preparation of Wool-g-Glycidyl Methacrylate with a Constructed –SH Groups/Ammonium Persulfate Redox System and Characterization

To explore suitable synthesis parameters of efficient graft copolymerization on wool, the disulfide bonds in wool chains were reduced to sulfhydryl groups by the treatment of thioglycolic acid to wool, and then wool-g-poly(glycidyl methacrylate) was prepared by graft copolymerization of wool with glycidyl methacrylate by building a redox system between sulfhydryl groups and ammonium persulfate. The wool-g-poly(glycidyl methacrylate) was characterized by the analyses of Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric and x-ray diffraction. Influences of molar concentrations of monomer and initiator as well as reaction temperature on grafting ratios were investigated. The experimental results showed that the sulfhydryl groups/ammonium persulfate redox system built could effectively initiate graft polymerization of lipophilic glycidyl methacrylate on the wool surface in an aqueous medium. The suitable process parameters of graft copolymerization were: 0.6 mmol/L molar concentration of glycidyl methacrylate, 3.0 mmol/L molar concentration of ammonium persulfate, and reaction temperature of 50 ℃. At the suitable parameters, the grafting ratio of wool-g-poly(glycidyl methacrylate) showed a maximum value of 195.8 %, indicating an efficient graft copolymerization was achieved. The copolymerization could reduce the degree of crystallinity of wool. The wool-g-poly(glycidyl methacrylate) had higher thermal stability than raw wool at a temperature of below 406 ℃ by performing the thermogravimetric analysis. Based on the results, we successfully built new sulfhydryl groups on the wool/ammonium persulfate redox system, prepared the wool-g-poly(glycidyl methacrylate), and this work will lay an important foundation for the application of wool-g-poly(glycidyl methacrylate) in the textile field.

Co-liquefaction of Tunçbilek lignite with algae (spirulina species): Effect of process parameters and characterization of chars and oils

Nowadays, to reduce the cost of coal liquefaction and to produce a new liquid fuel alternative to petroleum, it is considered a more convenient method to liquefy coal and biomass together instead of solely coal liquefaction. Liquefaction experiments were carried out by changing the solvent/solid ratio of 1/1–5/1, reaction temperature 320–400 °C, reaction time 30–90 min, and algae/lignite ratio in the range of 1/1–5/1. As a result of this study, the most suitable process parameters obtained by considering total conversion are; solvent/solid ratio 3/1, reaction time 60 min, algae/lignite ratio 4/1, and reaction temperature 380 °C. Under these conditions, the highest total conversion is approximately 80% and 77% in catalytic and non-catalytic conditions, respectively. Under non-catalytic conditions of co-liquefaction experiments due to the GC-MS results, cyclopentane (raw material of motor oil), pentadecane, 2-methyl-naphthalene, octa-ethylene glycol, ethylene oxide heptamer are the main products of optimum parameters aforementioned for oil. They are mainly used in fuel technology and used in the chemical industry as raw materials mean low-cost production as well.

Wear Investigation of Aluminum Alloy Surface Layers Fabricated through Friction Stir Welding Method

In this research paper, an effort was made to investigate the dry sliding wear rate of friction stir welded AA6262/AA5456 composite performed by the Taguchi approach. Wear experiments are carried out by selecting suitable process parameters such as load (LD), sliding speed (SS), and sliding distance (SE) to recognize the individual and combination effects of parameters. Orthogonal array L27 mode is applied to make numbers of experiments to find the extreme and minimum wear amount. The experimental works are conducted on Pin on Disc (POD) apparatus and measured the weight of samples before and after test for calculating wear rate (WR) and then various analyses are performed such as ANOVA, interaction plot between parameters, and regression model with support of MINITAB software. The results revealed that maximum wear rate is found as 0.01215 mm3/Nm at LD of 50 N, SE of 600 m, and SS of 4 m/s, whereas minimum 0.00414 mm3/Nm at the grouping process parameters which are LD of 30 N, SE of 400 m, and SS of 6 m/s. From the observation of ANOVA, the most significant factor is identified as load, followed by sliding distance, sliding speed, and combination of each parameter. The load is considered as main parameter which contributes about 83.75% to achieve the maximum wear rate of developed AA6262/5456 composites. The contribution of sliding distance and speed are 3.75% and 1.85%, respectively.

Prediction model of optimised process parameters for recycling carbon fibre composites

• Optimised process parameters for thermal recycling of thermoset carbon fibre reinforced polymer is presented. • Minimisation of carbon fibre degradation and maximisation of matrix removal is investigated. • Modelled results are validated with experimental and analytical results. • Improved integrity of recovered carbon fibre for achieving closed-loop recycling is discussed. A mathematical prediction model for identifying the most suitable process parameters for thermal recycling of thermoset carbon fibre reinforced polymer (TS-CFRP) composites is presented here. The process parameters of heating rate, maximum temperature and isothermal dwell time at the maximum temperature for recovery of carbon fibres depend on factors like the size of furnace and composite sample, composition and constituents of composites. The model considers such factors to give the most suitable process parameters so that the recovered carbon fibre has minimum degradation yet with maximum matrix removal. Modelled results on heat transfer, material conversion, radiation view factor, and predicted process parameters were verified with the experimental results. The model can provide a good prediction of the furnace process parameters and final matrix mass loss distribution by layer with an error percentage of five per cent. Using this prediction model with the TS-CFRP thermal recycling processes can assure conserving the original fibre value for closed loop recycling of carbon fibre.

Effects of selective laser melting parameters on surface quality and densification behaviours of pure nickel

The effects of laser power and scanning speed on the forming characteristic of scanning tracks, densification behaviours and surface roughness of pure nickel fabricated with selective laser melting (SLM) were studied. The results indicate that the scanning tracks showed continuous, regular and flat surface with increasing laser power and decreasing scanning speed in a specific range, which could avoid the defects (like holes and balling structures) forming in SLM processing. The optimal process window was identified as the scanning speed of 900 mm/s and the laser power of 255−275 W by comparing the surface qualities and densification behaviours. With the suitable processing parameters, the relative density could achieve 99.16%, the tensile strength was (359.49±2.74) MPa, and the roughnesses of the top and side surfaces were (12.88±2.23) and (14.98±0.69) μm, respectively.

Hydrogen as a Temporary Alloying Element for Establishing Specific Microstructural Gradients in Ti-6Al-4V

Parts of vehicles, such as landing gear components of aircrafts, are subject to growing demands in terms of sustainability via lightweight design and durability. To fulfill these requirements, the development of thermochemical processes is auspicious. Titanium alloys allow a heat treatment in hydrogen-containing atmosphere for temporary hydrogen alloying, often called thermohydrogen treatment (THT). The investigation presented intends to realize a local microstructure modification of Ti-6Al-4V by means of THT. The study aims to use hydrogen (H) as a promoter for changing the local distribution and morphology of strengthening precipitates during THT as well as the local grain size (microstructural gradient). Both shall improve the fatigue properties of the material after hydrogen degassing. To derive suitable thermohydrogen treatment process parameters, the resulting fatigue crack propagation resistance and fracture toughness after different solution heat treatments are determined experimentally and compared to each other. Moreover, various graded microstructures are evaluated after hydrogen uptake (hydrogenation) and hydrogen degassing (dehydrogenation) using numerically simulated hydrogen concentration profiles, observed hardness curves, metallographically determined microstructure gradients and the corresponding results of the phase analysis by means of X-ray diffraction. The study shows that hydrogenation at 500 °C and dehydrogenation at 750 °C enables the generation of a promising microstructural gradient.

Inline Weld Depth Evaluation and Control Based on OCT Keyhole Depth Measurement and Fuzzy Control

In an industrial joining process, exemplified by deep penetration laser beam welding, ensuring a high quality of welds requires a great effort. The quality cannot be fully established by testing, but can only be produced. The fundamental requirements for a high weld seam quality in laser beam welding are therefore already laid in the process, which makes the use of control systems essential in fully automated production. With the aid of process monitoring systems that can supply data inline to a production process, the foundation is laid for the efficient and cycle-time-neutral control of welding processes. In particular, if novel, direct measurement methods, such as Optical Coherence Tomography, are used for the acquisition of direct geometric quantities, e.g., the weld penetration depth, a significant control potential can be exploited. In this work, an inline weld depth control system based on an OCT keyhole depth measurement is presented. The system is capable of automatically executing an inline control of the deep penetration welding process based only on a specified target weld depth. The performance of the control system was demonstrated on various aluminum alloys and for different penetration depths. In addition, the ability of the control to respond to unforeseen external disturbances was tested. Within the scope of this work, it was thus possible to provide an outlook on future developments in the field of laser welding technology, which could develop in the direction of an intuitive manufacturing process. This objective should be accomplished through the use of intelligent algorithms and innovative measurement technology—following the example of laser beam cutting, where the processing systems themselves have been provided with the ability to select suitable process parameters for several years now.

Optimizing The Hot-Press Procedure Of High-Temperature Proton Exchange Membrane Fuel Cells For Adhesion Strength And Conductivity

As society considers alternatives to energy systems based on fossil fuel combustion, high-temperature proton exchange membrane (HT-PEM) fuel cells may play an important role in our future energy and transportation portfolio. When compared to low-temperature proton exchange membrane (LT-PEM) fuel cells, HT-PEM technology offers enhanced electrode kinetics, simplified water management, and most notably increased tolerance to fuel impurities such as carbon monoxide. However, compared to more conventional LT-PEM systems, less is known about the durability, performance, and fabrication of HT-PEM materials. Comprised of multiple layers, the membrane electrode assembly (MEA) is a fuel cell’s central component. In a fabrication process similar to LT-PEM MEAs, the proton-conducting membrane, electrodes, gas diffusion layers and sub gaskets are usually hot-pressed together. The parameters surrounding the hot-pressing operation can have a significant impact on the ultimate performance of the fuel cell, in addition to influencing process reliability and repeatability. In the current research, measurements of MEA thickness, impedance, and adhesion strength were obtained for samples over a range of conditions to optimize for the most suitable processing parameters. Testing in this study quantified the effects of hot-press time, temperature and pressure, within ranges of 1-10 minutes, 140 – 200oC, and 7.72 – 92.67 MPa (1120 - 13440 psi), respectively. After hot pressing, the MEA samples were tested for resistance with a 1260a Solartron impedance gain phase analyzer in tandem with a Solartron Ametek 12962a sample holder, and with a Scott internal bond tester for adhesion strength. Based on the results of these tests the optimal hot-press parameters were established, four 25 cm2 MEA were built and tested for performance with post-mortem analysis conducted utilizing scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). These measurements enabled interrogation of potential sources of conductivity loss associated with material layer delamination and/or dehydration of phosphoric acid in the polybenzimidazole (PBI) membrane. In this case, all tests were conducted at 140oC and the resulting material assembly was allowed to cool to room temperature in a nitrogen glove box prior to executing conductivity measurements (i.e., inverse of resistance). Our results have demonstrated that the optimal conditions for MEA hot-pressing for the HT-PEM system are around 170oC and 23.1 MPa for 5 minutes. Each curve in Figure 1 represents the performance of in-house MEAs, prepared using the optimized hot-pressing condition, with variation of platinum-on-carbon content (Pt/C) and total Pt loading. The data presented in Figure 1 demonstrate the effect of varying electrode thickness on MEA performance. Figure 1

Effect of temperature on crystallite size of hydroxyapatite powders obtained by wet precipitation process

In this investigation, HAp powders were synthesized using the wet chemical precipitation technique. The temperature of the heat treatment (80 °C, 120 °C, and 160 °C) and the addition of glutamic acid were the considered process parameters. After the reaction between the precursors calcium nitrate [Ca(NO3)2] and ammonium phosphate [(NH4)H2PO4], decantation of the residue, drying, and finally, heat treatment of the residue were done sequentially. X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) observations, and X-ray fluorescence (XRF) analysis were carried out to characterize the synthesized HAp powders. It was found that at a high heat treatment temperature plus the addition of glutamic acid are suitable process parameters to acquire uniform HAp powders with plate morphology and fibers with an average particle size of ∼100–200 µm. The Ca/P ratio obtained was like the hydroxyapatite present in the bones in the order of 1.72. This situation can be indicated as an essential advantage in the biocompatibility of the synthesized material. The use of glutamic acid suggests crystal growth in a preferential direction as reported in our previous work. The manufacture of hydroxyapatite, especially in powder, is of great interest in developing additive manufacturing systems for the biomedical market.

A Study on Friction Stir Processing Parameters of Recycled AA 6063/TiO2 Surface Composites for Better Tribological Performance

This work aims to determine and select the suitable friction stir processing parameters for recycled aluminum alloy 6063 surface composites reinforced with titanium dioxide for better tribological performance. A medium range of processing parameters (1200–2000 rpm, 25–45 mm/min) were used to compare with a unique relatively high rotational speed of 2442 rpm and feed rate of 50 mm/min for the sample fabrication. The surface composites’ microhardness was measured and the friction and wear performance were tested using the pin-on-disc tribo-tester under starved lubrication conditions. The results show that surface composites produced at a high rotational speed of 2442 rpm and feed rate of 50 mm/min improved 45% in surface microhardness and reduced the friction coefficient and wear rate by 39% and 73%, respectively, compared to the substrate material.

Study on the characteristics of high temperature alloy surface profile grinding process

High-temperature alloy profile grinding is mainly used in the machining of aero-engine turbine structural parts, which require high surface quality and high machining efficiency. However, the process ability of machining high-temperature alloys is poor. For this reason, this paper conducts experimental research on the surface profile grinding process of high-temperature alloys to meet the surface quality and machining efficiency requirements of high-temperature alloy structural parts. Using a precision profile grinding machine, WA and SG grinding wheels are selected for profile grinding tests on three types of workpieces with curved surfaces: flat, convex, and concave. Each shape of the workpiece was shaped-ground using WA and SG grinding wheels separately. The orthogonal experimental method was used to perform profile grinding by changing three factors: grinding wheel speed, feed, and backlash. The surface roughness after grinding was measured and compared, and the most suitable process parameters for grinding three curved workpieces with WA and SG grinding wheels were obtained by comparing the surface quality and machining efficiency. The grinding strategy is also given for surface roughness and machining efficiency. It provides a basis for the improvement of the quality and efficiency of high-temperature alloy forming and grinding.

Optimizing The Hot-Press Procedure Of High-Temperature Proton Exchange Membrane Fuel Cells For Adhesion Strength And Conductivity

High-temperature proton exchange membrane (HT-PEM) fuel cell systems are under active development for a variety of mobile and stationary power applications. Measurements of membrane-electrode assembly (MEA) thickness, impedance, and adhesion strength were obtained for samples fabricated over ranges of conditions to optimize for the most suitable processing parameters. Testing quantified the effects of hot-press time, temperature, and pressure, over ranges of 1-10 minutes, 140 – 200oC, and 7.72 – 92.67 MPa, respectively. After hot pressing, MEA samples were tested for resistance with a Solartron impedance analyzer, and for adhesion strength with a Scott internal bond tester. From these results, optimal hot-press parameters were established and four 25 cm2 MEAs were fabricated and tested. Post-pressing analysis of MEAs was conducted using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. Our results demonstrate that the optimal conditions for MEA hot-pressing for the HT-PEM system are around 170oC and 23.1 MPa for 5 minutes.

Preparation of Al2O3 magnetic abrasives by combining plasma molten metal powder with sprayed abrasive powder

Magnetic abrasives play a significant role in finishing processes; however, existing magnetic abrasive particles have limited their application in industry due to poor grinding performance and low service life. In this paper, high-performance iron-based spherical Al2O3 magnetic abrasives were prepared via combining plasma molten metal powder with sprayed abrasive power. Firstly, the effects of the co-gas flow rate and current on the overall melting state of the iron matrix powder were studied to obtain the suitable process parameters; then, the magnetic abrasives were prepared by increasing the hydrogen flow rate by 25% under this process parameter, and the microscopic morphology, phase composition, bonding mode, magnetic permeability and particle size distribution of the magnetic abrasives were analyzed; finally, the grinding experiments were conducted on 316 L stainless steel. The results show that the overall fusion state of the iron matrix powder is good under the parameters of current 700 A, argon flow rate 1000 L/h and hydrogen flow rate 80 L/h. The magnetic abrasives have a very high sphericity, and the alumina abrasives with sharp cutting edges are uniformly and compactly embedded into the iron matrix and form a tight mechanical bond with it; the particle size distribution of the magnetic abrasives accounts for 85% of the iron matrix; the magnetic abrasives have excellent grinding performance. The magnetic abrasives preparation approach described in this paper has the characteristics of economy and high performance, and is expected to be used for industrial mass production.

Effect of High-Humidity Hot Air Impingement Steaming on Cistanche deserticola Slices: Drying Characteristics, Weight Loss, Microstructure, Color, and Active Components.

Cistanche deserticola is one of the most precious herbal medicines and is widely used in the pharmaceutical and healthy food industries. Steaming is an important step prior to drying in the processing of C. deserticola. This research investigated the effects of high-humidity hot air impingement steaming (HHAIS) parameters such as temperature, time, and relative humidity (RH) on drying characteristics, weight loss, color, microstructure, and active components of C. deserticola slices. The results showed that the steaming process caused a weight loss in C. deserticola; however, increasing the RH reduced the weight loss. Starch gelatinization observed from the microstructure of the steamed samples explained their long drying time. The Page model can well fit the drying process with a high R2 (>0.956) under the drying conditions of 60°C and 6 m/s. Steaming increased the content of phenylethanoid glycosides, and the highest content was obtained at 95°C and 60% RH for 20 min, 75°C and 70% RH for 20 min, and 75°C and 60% RH for 30 min. The steamed samples appeared in an oil black color. When the color difference (ΔE) values were in the range of 16.79–20.12, the contents of echinacoside and acteoside reached the maximum. Steaming at 95°C and 60% RH for 20 min, 75°C and 70% RH for 20 min, and 75°C and 60% RH for 30 min are the optimum process conditions. The results from this work provide innovative steaming technology and suitable processing parameters for producing C. deserticola decoction pieces with a high quality, which will broaden its potential application in the functional health food industry.

In-situ microstructural evolution during quenching and partitioning of a high-carbon steel by high-temperature X-Ray Diffraction

Carbon partitioning from martensite to austenite is essential for austenite stabilization during quenching and partitioning (Q&P), while a few competitive phenomena, such as bainitic transformation and carbide precipitation, alter the microstructural evolution. So, there is a need of using in-situ in combination with ex-situ characterisation techniques to understand the C partitioning at high temperature in relation to simultaneous competitive phenomena that might occur during the partitioning stage.In this study, microstructural evolutions of a medium carbon steel ( 0.6C–1.6Si–1.25Mn–1.75Cr wt%) during Q&P treatment were investigated by using an in-situ High-Temperature X-Ray Diffraction (HTXRD) equipment at three partitioning temperatures. Results confirmed that carbon enrichment of austenite at 280 and 400 ℃ originates from partial carbon depletion from martensite and bainitic transformation, while partitioning at 500 ℃ results in the complete depletion of carbon from initial martensite and ferrite formation. Short diffusion distance (~0.13 µm) of carbon at 280 ℃ caused a poor carbon homogenization of austenite and formation of 8 vol% fresh martensite after final quenching. High Si content of the steel stabilized transitional carbides and, concurrently, suppressed Fe3C formation during Q&P. The outcome of this study could contribute to the design of suitable chemistry and process parameters for producing quenched and partitioned steels.

Process optimization, microstructure and microhardness of coaxial laser cladding TiC reinforced Ni-based composite coatings

Since the precursors for coaxial laser cladding (LC) can be easily customized, less waste, and flexibly applied to the surface of complex parts, LC is a practical and promising approach to fabricate metal matrix composite (MMC) coatings for surface modification or repair compared with selective laser melting, preset powder cladding, gas tungsten arc welding. The precursors for LC MMC coatings are composed of an optimized single alloy powder, hard particles or related elements. However, the process for LC MMC coatings is the same as that for single alloy powder. Since the added materials usually affect the quality of the laser beam, the flow characteristics and the solidification process of the melt pool, the process parameters for LC MMC coatings are often not optimal. Therefore, the coarse TiC particles were firstly added to the commercial Ni45 powder, and the Taguchi method and empirical statistical model are employed to optimize process parameters for LC MMC coatings. A reliable processing map for customized precursors was obtained. Finally, the single-layer multi-track TiC-reinforced MMC coatings were fabricated to verify the correctness of mathematical models. The suitable process parameters combination for LC Ni-based MMC coatings are laser powder of 380 W, scanning speed of 5 mm/s, and powder feed rate of 243.7 mg/s. Moreover, the microhardness of the optimized MMC coating is about 520 HV0.3, which is about 2.5 times that of the substrate.

Time‐Resolved Orientation and Phase Analysis of Lead Halide Perovskite Film Annealing Probed by In Situ GIWAXS

AbstractScalable thin‐film deposition methods are increasingly important for hybrid lead halide perovskite thin films. Understanding the structure evolution during non‐equilibrium processes helps to find suitable materials and processing parameters to produce films with well‐performing optoelectronic properties. Here, spin‐cast and slot‐die coated bilayers of lead iodide (PbI2) and methylammonium iodide (MAI) are investigated by in situ grazing‐incidence wide‐angle X‐ray scattering during the thermal annealing process, which converts the bilayer into methylammonium lead iodide (MAPI). Photoluminescence (PL) and UV/Vis measurements show increasing crystallinity during the annealing process and a slight PL red‐shift of the spin‐cast film, attributed to crystallite coalescence that is not prominent for the slot‐die coated film. The disintegration of the solvent‐precursor complex (MA)2(Pb3I8) ⋅ 2 DMSO and conversion into perovskite are followed in situ and differences in the morphology and time evolution are observed. In both, spin‐cast and slot‐die coated thin‐films, the isotropic orientation is dominant, however, in the slot‐die coated films, the perovskite crystallites have an additional face‐on orientation ((110) parallel to substrate) that is not detected in spin‐cast films. An Avrami model is applied for the perovskite crystal growth that indicates reduced dimensionality of the growth for the printed thin films.

Selective Laser Melting of Pure Ag and 925Ag Alloy and Their Thermal Conductivity

Due to the high reflectivity of Ag to infrared lasers, there is little research focused on the manufacturing of Ag and Ag alloys by selective laser melting (SLM) technique. In this paper, the manufacturing characteristics, microstructure, and thermal conductivity of SLMed Ag, 925Ag, and their heat-treated parts were studied. With the suitable processing parameters, Ag and 925Ag samples with relative densities of 91.06% and 96.56%, respectively, were obtained. Due to the existence of non-molten particles inside the samples and local high energy density of the laser during the processing, a large number of irregular pores and micropores were formed in the microstructures. XRD analysis shows that no phase transition occurred in the annealed Ag and solution-treated 925Ag parts, as compared to their as-built conditions. The SLMed Ag exhibited fine equiaxed grains, while both columnar grains and elongated lath grains existed in the SLMed 925Ag parts. The annealed Ag and solution-treated 925Ag exhibited large equiaxed grains. Due to the grain growth that occurred in the microstructure, the thermal conductivity of Ag increased by 11.35% after completing the annealing treatment. However, that of 925Ag decreased by 17.14% after completing the solid solution treatment, due to the precipitation of the strengthening phase at grain boundaries. A comparison of the thermal conductivities of Ag and 925Ag shows that the influence of the materials on the obtained thermal conductivities was more pronounced than that of the porosity.