Stainless Steel Micro Research Articles

Influence of ECM process parameters on SS316 material

Electro-Chemical Machining (ECM) seems to be a hopeful technique in the production area of automobile manufacturing and other productions. In recent years, the demand for stainless steel (SS) micro products and components has evolved significantly in fields such as biotechnology, electronics, optics, medicine and so on. This stainless-steel material is ideal for hygienic environments because it is easily sterilized and corrosion resistant. The process parameters of ECM for stainless steel material are investigated experimentally in this study. The SS-316 alloy was chosen to influence the electrochemical machining process with different electrodes and to investigate process parameters using SEM analysis. The tool material has been changed to investigate the improved quality of ECM process parameters.

Tensile and Pull-Out Behavior of Steel Reinforced Grout Connectors

Mortar-based composites are an emerging technology for the repair and strengthening of reinforced concrete and masonry structures. In most cases, the effectiveness of the retrofitting work relies on the substrate-to-composite bond capacity but in some applications, connectors are also used to prevent debonding and improve the performance of the retrofitted structure. Indeed, the use of connectors is recommended by design guidelines and suppliers are required to test them for acceptance. The paper presents a laboratory investigation on steel reinforced grout connectors, made by rolling ultra-high tensile strength steel textiles, comprising either galvanized or stainless-steel micro cords. Tensile tests were first carried out for mechanical characterization. Pull-out tests were then performed on connectors installed in holes drilled in wall panels and injected with either cement or lime mortars. Concrete, tuff masonry, brickwork and limestone masonry were used as substrate materials. Test results are commented to analyze the effect of textile rolling on tensile response, of textile and matrix properties on pull-out strength and failure mode, as well as to highlight their significance for design purposes.

Analysis of Micro-Machining Process for External Thread of Micro Round Tube.

This study aims to analyze the stainless steel micro round tube external threading process for the influence of different outer threading pitches (0.25 mm, 0.4 mm) and outer diameters (Ø1.9, Ø1.94, Ø2). This study also analyzes the effects of different friction factors (0.1, 0.3, 0.5, 0.7, and 0.9) and different tube thicknesses (0.4, 0.45, 0.5, 0.55, and 0.6 mm) on the threading process. This study considers size effect to use corrected material parameters for the microtube to conduct the finite element analysis by DEFORM-3D software. The goal is to understand stainless steel (SUS304) micro round tube threading and the difference by using macro material parameter analysis. The historic forming data from the simulation and experiment of threading processing are presented, and the corresponding stress/strain distribution and thread shape are also calculated. The experiment results are compared to the simulation results to verify the reliability of this analysis method. The result shows that the torque/stress/strain obtained by the modified model is always lower than by Swift’s model. It means that the size effect can be considered to apply on the forming process and provided proper torque to form the external thread of the micro round tube, e.g., the maximum torque of the round die for M2 × 0.25 occurs over the fourth stroke. For the influence of the outer diameter of the micro round tube, the larger diameter induces the larger maximum torque on the round die for M2 × 0.4, but for the smaller pitch of M2 × 0.25, the larger maximum torque is not influenced by the diameter of the tube. When the pitch of the round die is increased, the torque, stress and strain are also increased relatively. As the friction factor and torque between the round die and tube increase, the stress and strain become lower. Changing the tube thickness will not significantly change the torque, the stress, and the strain. These results guide the simulation and experiment of optimized micro round tube threading development and design to reduce cost and increase product quality.

Research on the synergistic effect of megasonic and particles in through mask electrochemical etching process

Through-mask electrochemical etching (TMEE) is one of the main methods to fabricate metal microstructures array in large scale. In deep metal microstructure etching process, lateral corrosion problem seriously affects the etching localization. In this paper, megasonic and particle combined through mask electrochemical etching (MP-TMEE) method was proposed to improve the etching localization in TMEE process. Experimental results show that the etching factor (EF) was greatly improved by MP-TMEE method compared to traditional TMEE. With the use of MP-TMEE, when the feature size of the mask was 100 μm, the average diameter and depth of the etched micro pits were 148.7 μm and 59.9 μm. The use of MP-TMEE instead of TMEE leads to an increase in EF from 1.58 to 2.50. Besides, the mechanism of the synergistic effect of megasonic and the particles in MP-TMEE process was investigated. An erosion theoretical model of passivation film was established and verified by electrochemical impedance spectroscopy (EIS) method. The measurement results of EIS show that the micro pit depth and the passivation film resistance have the opposite variation trend, and the passivation film resistance measurement results are consistent with the trend of the theoretical model. Finally, microstructure arrays involving stainless steel micro pit array and micro pillar array, copper micro pit array and micro pillar array were fabricated using MP-TMEE method.

Pd-Fe3O4/RGO: a Highly Active and Magnetically Recyclable Catalyst for Suzuki Cross Coupling Reaction using a Microfluidic Flow Reactor

There are several crucial issues that need to be addressed in the field of applied catalysis. These issues are not only related to harmful environmental impact but also include process safety concerns, mass and heat transfer limitations, selectivity, high pressure, optimizing reaction conditions, scale-up issues, reproducibility, process reliability, and catalyst deactivation and recovery. Many of these issues could be solved by adopting the concept of micro-reaction technology and flow chemistry in the applied catalysis field. A microwave assisted reduction technique has been used to prepare well dispersed, highly active Pd/Fe3O4 nanoparticles supported on reduced graphene oxide nanosheets (Pd-Fe3O4/RGO), which act as a unique catalyst for Suzuki cross coupling reactions due to the uniform dispersion of palladium nanoparticles throughout the surface of the magnetite - RGO support. The Pd-Fe3O4/RGO nanoparticles have been shown to exhibit extremely high catalytic activity for Suzuki cross coupling reactions under both batch and continuous reaction conditions. This paper reported a reliable method for Suzuki cross-coupling reaction of 4-bromobenzaldehyde using magnetically recyclable Pd/Fe3O4 nanoparticles supported on RGO nanosheets in a microfluidic-based high throughput flow reactor. Organic synthesis can be performed under high pressure and temperature by using a stainless steel micro tubular flow reactor under continuous flow reaction conditions. Optimizing the reaction conditions was performed via changing several parameters including temperature, pressure, and flow rate. Generally, a scalable flow technique by optimizing the reaction parameters under high-temperature and continuous reaction conditions could be successfully developed.

Testing Conjugate Conduction in Stainless Steel Micro Heat Sink

In this paper the microchannel setup to study longitudinal conduction phenomenon was developed and tested. Circular microchannels, 18 in number (hydraulic diameter = 400±09μm, Length=40±0.4 mm) were manufactured using EDM process in square piece made of stainless steel material to study forced convection using water and ethanol as coolant. The setup was tested under uniform heat flux conditions for the identification of backward conduction phenomenon. The test rig was also able to reproduce the data. The temporal variations observed in coolant temperatures during transient conditions at various locations provided encouraging results. Rise in the temperature of the coolant at the inlet location for various experimental conditions was observed. Higher degree of axial conduction was observed in ethanol relative to water.

Quantification of rare earth elements with low pressure laser induced breakdown spectroscopy employing subtarget supported micro mesh sample holder

Presented in this paper are the results of practical application of laser-induced breakdown spectroscopy to sensitive detection of rare earth elements (REEs) in trace amounts using a Cu subtarget supported stainless steel micro mesh (SSMM) powder sample holder. Powder samples containing separately a number of REEs (Yb, Y, Eu, and La) are measured using the SSMM sample holder and a 68 mJ ns Nd:YAG laser with −5 mm defocused irradiation in 1.3 kPa ambient air. All the resulted emission spectra are shown to exhibit excellent spectral quality featuring well resolved sharp spectral lines with low background and without spectral interference from the sample holder. Further measurements of additional powder samples with varied content of REEs are performed to reveal the existence of linear calibration lines with extrapolated zero intercept and well below 100 ppm detection limits promising for practical quantitative REEs analysis, particularly for sensitive field exploration of REEs.

Investigating the potential for transisomerisation of trycresyl phosphate with a palladium catalyst and its implications for aircraft cabin air quality

The quality of aircraft cabin air has been an area of concern for several decades. Many investigations have linked the presence of organophosphates in air to Aerotoxic Syndrome with adverse symptoms reported by thousands of aircraft crew across the globe. Currently the source of organophosphates has been under debate, with studies pointing towards tricresylphosphates (TCP) in aircraft oil as the main source due to leaks in engine seals resulting in fumes entering the cabin. However, comparisons of oil and cabin samples have shown that the cabin samples contain a much higher proportion of ortho-substituted TCP than is commonly detected in oil. The aim of this experiment was to investigate the potential for palladium catalysts (present in aircraft air conditioning systems) to convert meta- and para-substituted TCP to produce ortho-substituted TCP through transisomerisation. This experiment was performed in a controlled laboratory setting aimed to represent the conditions likely to be experienced in aircraft. Samples were introduced to a stainless steel micro reactor tube containing the pelletized palladium catalyst using a HPLC pump with a 0.2 ml/min feed flow rate. The temperature maintained at 400 °C over a period of 1 h and samples collected using a condensing vesicle. These were then diluted and transferred to a 2 mL vial for analysis by gas chromatography mass spectrometry. No evidence supporting the transisomerisation of tricresylphosphate was obtained. This indicates that more emphasis should be placed on identifying other potential sources of ortho substituted TCP.

Shock wave plasma generation in low pressure ambient gas from powder sample using subtarget supported micro mesh as a sample holder and its potential applications for sensitive analysis of powder samples

We present in this report the results of experimental study on the spectrochemical analysis of powder samples using subtarget supported micro mesh (SSMM) sample holder in low pressure ambient gases. The study is substantiated by establishing the analyte excitation mechanism with the evidence of shock wave plasma generation and the high temperature induced subsequently required for the thermal excitation and emission of the ablated atoms. The application of SSMM sample holder using Cu subtarget and stainless steel micro mesh to a number of powder samples in low pressure ambient gases are shown to produce generally sharp emission lines with low background, without suffering from intensity reduction and matrix effect commonly found in the use of pelletized powder samples. The same excellent spectral quality is demonstrated by its application to the analysis of rice samples which is the major staple diets in a large number of countries. In particular the analysis of Zn in rice is shown to exhibit a linear calibration line with extrapolated zero intercept and a detection limit of <0.87 μg/g which is promising for quantitative analysis.

Measurement and simulation of the hybrid structure gaseous detector gain

As one of the most popular micro pattern gaseous detectors, gas electron multiplier (GEM) has been extensively studied and applied in recent years. The studies of the detector gain measurement and simulation are important, especially on a low gain scale. Traditionally, the gain measurement is realized by measuring the current or the pulse height spectrum. The former needs complicated electronic chain calibration and the latter needs necessarily to calculate the primary electron number. In this paper, an alternative method to determine the effective gain of GEM is introduced. The GEM gain can be precisely achieved through a gaseous detector of hybrid structure which combines GEM with micro-mesh gaseous structure (MM). The hybrid structure is called GEM-MM for short. The GEM-MM detector consists of drift cathode, standard GEM foil, stainless steel micro mesh, and readout anode. In this detector, the space between the cathode and the GEM foil is called drift gap and the other space between the GEM foil and the mesh is named transfer gap. When the X-rays irradiate into the gas volume of GEM-MM, the primary ionization occurs in both regions. Photoelectrons in the drift gap transfer from the drift region to amplification sensitive areas of the GEM and the MM detector while those in the transfer region are only amplified by the MM detector. In the energy spectrum of 55Fe, there is a clear energy profile including two sets of peaks. The gain of GEM can be easily obtained from the energy spectrum. Meanwhile, detailed simulations are carried out with Garfield++ software package. Simulation of the electron transport parameters has been optimized. and the gains of GEM detector are also calculated for three different gas mixtures. Experimental results of the gains ranging from 3 to 24 are obtained. The gains of GEM under different working voltages are studied precisely from the spectrum measurements. The Penning transfer rate could reach 0.32±0.01 when the simulated value matches the measurement within 1σ error.

High temperature Gleeble microtensile testing of metallic micro specimens

Abstract Engineering of micro parts is an increasingly important area of industrial activity and this field is rapidly developing further. Thus, the simulation of micro parts also becomes more and more important. As reliable material data is required to obtain accurate simulation results, test setups are also necessary to determine the material properties. An experimental setup for microtensile testing of stainless steel micro specimen (i. e., specimen with at least one dimension below 1 mm) to obtain material data in the temperature range from 20 to 350 °C is presented herein. Heating of the specimen is based on Joule (resistive) heating as it is done in macroscopic testing in Gleeble machines. Contactless measurement of temperatures is conducted by an infrared (IR) camera and the determination of strain by a combination of optical microscopy and digital image correlation (DIC). First samples were made from the stainless steel 17-4PH and the results obtained are presented and discussed in comparison with macroscopic properties of this material.

Stainless steel micro fuel cells with enclosed channels by laser additive manufacturing

This study introduces the first steel micro fuel cells with enclosed channel flowfield made by laser additive manufacturing. These are also the first microfluidic devices with enclosed channels made from stainless steel by additive manufacturing. One important benefit of such fabrication methods is ultrafast prototyping, which we made use of in this study to optimize the performance of our fuel cells. The fabrication process consists of preparing a 3D model using a suitable computer-aided design software and then uploading the model file to the laser additive manufacturing machine. This process requires minimal manual intervention. The use of stainless steel as the fabrication material results in extremely durable, robust, chemically and thermally stable devices. Micro fuel cells with three different stainless steel flowfields were fabricated and characterized, two of which with enclosed channels, and one with traditional open grooves. Both enclosed channel flowfield fuel cells produced significantly higher power and current densities compared to the open groove counterpart: the maximum current density obtained was 1.515 A cm−2 and maximum power density was 363 mW cm−2.

Control of the Nano-Particle Weight Ratio in Stainless Steel Micro and Nano Powders by Radio Frequency Plasma Treatment

This study describes how to make stainless steel hybrid micro-nano-powders (a mixture of micro-powder and nano-powder) using an in situ one-step process via radio frequency (RF) thermal plasma treatment. Nano-particles attached to micro-powders were successfully prepared by RF thermal plasma treatment of stainless steel powder with an average size of 35 μm. The ratio of nano-powders is estimated with a two-dimensional fluid simulation that calculates the temperature profile influencing the rate of surface evaporation. The simulation is conducted to determine the variation of the input power and the distance from the plasma torch to the feeding nozzle. It was demonstrated experimentally that the nano-powder ratio in the micro-nano-powder mixture can be controlled by adjusting the feeding rate, plasma power, feeding position and quenching effect during plasma treatment. The ratio of nano-particles in the micro-nano-powder mixture was controlled in a range from 0.1 (wt. %) to 30.7 (wt. %).

Micro-Shock Tube 유동에 대한 실험적 연구

The flow characteristics in micro shock tube are investigated experimentally. Studies were carried out using a stainless steel micro shock tube. Shock and expansion wave was measured using 8 pressure sensors. The initial pressure ratio was varied from 4.3 to 30.5, and the diameter of tube was also changed from 3mm to 6mm. Diaphragm conditions were varied using two types of diaphragms. The results obtained show that the shock strength in the tube becomes stronger for an increase in the initial pressure ratio and diameter of tube. For the thinner diaphragm, the highest shock strength was found among varied diaphragm condition. Shock attenuation was highly influenced by the diameter of tube.

Sintering behavior of 316L stainless steel micro–nanopowder compact fabricated by powder injection molding

The densification and grain growth behavior of powder injection molded 316L stainless steel micro–nanopowder were investigated in terms of microstructural development. The sintered density of the micro–nanopowder sample increased remarkably in the temperature range of 1000 to 1100°C due to the sintering effect of nanopowders which increased the number of grain boundaries acting as high material transport path. A near full density of 98% TD was obtained after sintering at 1100°C for 5h with the average grain size less than 10μm, indicating that there was no drastic grain growth. The presence of nanopowders in micro–nanopowder played decisive role in the entire sintering process by enhancing densification but suppressing grain growth. These effects open up the possibility of using micro–nanopowder feedstock to control the sintering behavior of powder injection molding products with full density and fine microstructure.

COMPRESSIVE MECHANICAL BEHAVIORS OF HYBRID COMPOSITE MATERIALS BASED ON MICRO LATTICE STRUCTURE AND RUBBERLIKE MATERIALS

ABSTRACT This article investigates compressive and energy absorption characteristics for composites obtained by filling stainless steel micro lattice materials, manufactured via the selective laser melting method, with three different rubbers, including room temperature vulcanization silicone, natural rubber, and neoprene rubber. At the stage of building the composites with natural and neoprene rubbers, an experimental setup was designed for these two rubbers to be infiltrated into lattice spaces under vulcanization temperatures and high pressures. The results showed that the composites with silicone and neoprene matrix had a quite similar response as well as a seriously enhanced energy absorbing capacity and plateau stresses, in comparison with the corresponding lattice structures, for especially small sized lattice components. Also, the compression tests of the composite with natural rubber matrix clearly show that there should be no large differences between the individual mechanical properties of each component in the composite, and, in this way, the contribution of each component on the mechanical behavior of composite should be guaranteed to provide the satisfying performance.

Laser additive manufacturing of stainless steel micro fuel cells

This paper introduces laser additive manufacturing as a new method for the fabrication of micro fuel cells: The method opens up the capability of ultrafast prototyping, as the whole device can be produced at once, starting from a digital 3D model. In fact, many different devices can be produced at once, which is useful for the comparison of competing designs. The micro fuel cells are made of stainless steel, so they are very robust, thermally and chemically inert and long-lasting. This enables the researcher to perform a large number of experiments on the same cell without physical or chemical degradation. To demonstrate the validity of our method, we have produced three versions of a micro fuel cell with square pillar flowfield. All three have produced high current and power density, with maximum values of 1.2 A cm−2 for the current and 238 mW cm−2 for power.

Heat transfer correlation for flow boiling in small to micro tubes

There is a large discrepancy in the open literature about the comparative performance of the existing macro and microscale heat transfer models and correlations when applied to small/micro flow boiling systems. This paper presents a detailed comparison of the flow boiling heat transfer coefficient for R134a in stainless steel micro tubes with 21 macro and microscale correlations and models. The experimental database that was used in the comparison includes the data for 1.1 and 0.52mm diameter tubes, mass flux range of 100–500kg/m2s and system pressure range 6–10bar obtained in the course of this study. The effect of the evaporator heated length on the comparative performance of the correlations and models was investigated using three different lengths of the 1.1mm diameter tube (L=150, 300 and 450mm). This comparative study demonstrated that none of the assessed models and correlations could predict the experimental data with a reasonable accuracy. Also, the predictability of most correlations becomes worse as the heated length increases. This may contribute in explaining the discrepancy in the comparative performance of the correlations from one study to another. A new correlation is proposed in the present study based on the superposition model of Chen. The database used in developing the correlation consists of 5152 data points including the current experimental data and data obtained previously with the same test rig, fluid and methodology for tubes of diameter 4.26, 2.88, 2.01mm. The new correlation predicted 92% of the data within the ±30% error bands with a MAE value of 14.3%.

Using micro deep drawing with ironing stages to form stainless steel 304 micro cups

The needs of stainless steel 304 micro cups have been increasing tremendously due to the trend of miniaturization in medical and electronic devices, etc. For application purpose, it is highly desired to have stainless steel micro cups with high CH/OD (cup height/outer diameter) ratios. Due to the constraints of the limit draw ratio (LDR) of stainless steel 304 sheets in micro deep drawing, forming a micro cup with high CH/OD ratio at room temperature cannot be achieved by using a single stage deep drawing die. A process consisting of one micro deep drawing and two ironing stages was proposed for achieving this goal; three micro dies were designed, fabricated and used for experimental validation. A series of experiments were conducted by using the stainless steel 304 sheets of 200μm thickness annealed at four different temperatures to understand the influence of size effects on this process for generating knowledge, know-how and technologies to form high quality stainless steel micro cups with large CH/OD ratio. No lubricant was used in this study. It was proven that the proposed process is a robust process as long as the sheets are annealed at the temperature no less than 900°C for more than 3min.

Plastic Micro Features Produced by Microwelding Machine

The method of using microwelding machine to fabricate micro features on a stainless steel micro mould has been studied. The micro features obtained from molding using an ultrasonic microwelding machine have shown distinctive characteristics. The microflow behavior of polymer melt during the microwelding process is also studied. The micro molds of 0.2mm thick and through holes of 0.05mm and 0.2mm in diameters were used. Results show micro features can be produced using the microwelding machine with molding speed comparable to that of micro injection molding.