Silicone Rubber Gasket Research Articles

Chemical aging of sealing gasket of proton exchange membrane fuel cell

AbstractAs the key sealing part of proton exchange membrane fuel cell (PEMFC), the gasket is easily damaged in acidic solution and wet air for a long time in PEMFC, resulting in unsafe and unstable operation of PEMFC. In this paper, the regular solution (RS) and accelerated durability test (ADT) solution in PEMFC were prepared to study the aging damage process of silicone rubber gasket, and the attenuated total reflection Fourier transform infrared spectrometer (ATR‐FTIR) was used to analyze the surface changes of gaskets soaked in solutions. The results showed that the weight loss of samples increased with the soaking time in both ADT solution and RS solution, and the damage of samples in ADT solution was faster and more serious than that in RS solution. Meanwhile, the microstructure diagram also indicated that the damage of the samples in ADT solution was more serious than that in the RS solution. The ATR‐FTIR analysis results showed that the intensity of characteristic wave peaks of samples at 706, 787, 867, 1006, 1071, 1260, and 2961cm−1 in ADT solution decreased faster than that in RS solution, which was consistent with the results of weight analysis and microstructure analysis.

Machine Vision and Deep Learning Based Rubber Gasket Defect Detection

This study develops an automated optical inspection system for silicone rubber gaskets using traditional rule-based and deep learning detection techniques. The specific object of interest is a 5 mm × 10 mm × 5 mm mobile device power supply connector gasket that provides protection against foreign body inclusion and water ingression. The proposed system can detect a total of five characteristic defects introduced during the mold-based manufacture process, which range from 10-100 μm. The deep learning detection strategies in this system employ convolutional neural networks (CNN) developed using the TensorFlow open-source library. Through both high dynamic range image capture and image generation techniques, accuracies of 100% and 97% are achieved for notch and residual glue defect predictions, respectively.

Sealing performance analysis of composite gaskets made of silicone rubber filled with ramie natural fibers

Silicon rubber gaskets are commonly used in many industries for low pressure sealing conditions only. The research studies about the sealing performance improvement of a novel composite gasket made of the silicone rubber filled with ramie natural fibers in a bolted joint connection. In this research the sample of gasket consists of 4 different types of gasket i.e. a pure silicone rubber gasket and the silicone rubber composite gasket with 1, 2 and 3 layers of ramie fiber woven. The gaskets are tested using a water pressure testing equipment with a variation of internal fluid pressure and difference torques at 8 N.m, 12 N.m, 16 N.m and 20 N.m. The sealing performance is measured based on the maximum fluid pressure that can be hold by the gaskets before the fluid leaking occurred. The results show that the silicone rubber composite gaskets have better sealing performance comparing with the pure silicone rubber gaskets where the silicon rubber gaskets capable to hold the internal fluid pressure until around 5 times rather than pure silicon rubber gaskets (0.17 MPa comparing with 0.90 MPa). On the other hand the sealing performance of the composite gasket with 3 layers is almost 2 times better than the composite gasket with 1 layer and around 1.5 times better than the composite gasket with 2 layer of fiber woven.

Stress relaxation behavior and life prediction of gasket materials used in proton exchange membrane fuel cells

Silicone rubber gaskets are employed to keep fuel gases and oxidation in their own zones. Due to the viscosity and elasticity, the assembly force could relax when the silicone rubber is compressed in a proton exchange membrane fuel cell. In this work, the stress relaxation behavior of silicone rubber samples is studied under different temperatures and simulated operating conditions. The results show that the stress relaxes exponentially with time at 25% strain level, especially at higher temperature or with higher acid concentration solution. The three-term Prony series can simulate the viscoelastic behavior well, and the Master curves are established by applying a time-temperature superposition method to estimate the life of the samples. It can save approximately 50% and 78% of the test time when an operating temperature and acid solution are chosen appropriately.

Reliability of spring interconnects for high channel-count polyimide electrode arrays

Active neural implants with a high channel-count need robust and reliable operational assembly for the targeted environment in order to be classified as viable fully implantable systems. The discrete functionality of the electrode array and the implant electronics is vital for intact assembly. A critical interface exists at the interconnection sites between the electrode array and the implant electronics, especially in hybrid assemblies (e.g. retinal implants) where electrodes and electronics are not on the same substrate. Since the interconnects in such assemblies cannot be hermetically sealed, reliable protection against the physiological environment is essential for delivering high insulation resistance and low defusibility of salt ions, which are limited in complexity by current assembly techniques. This work reports on a combination of spring-type interconnects on a polyimide array with silicone rubber gasket insulation for chronically active implantable systems. The spring design of the interconnects on the backend of the electrode array compensates for the uniform thickness of the sandwiched gasket during bonding in assembly and relieves the propagation of extrinsic stresses to the bulk polyimide substrate. The contact resistance of the microflex-bonded spring interconnects with the underlying metallized ceramic test vehicles and insulation through the gasket between adjacent contacts was investigated against the MIL883 standard. The contact and insulation resistances remained stable in the exhausting environmental conditions.

On the corrosion behavior of Al2Cu by local electrochemical impedance spectroscopy using droplet cell microscopy

In this short communication, we study the electrochemical behavior of an individual Al2Cu intermetallic phase (coexisting with α-Al) in 0.1 M NaCl solution (with and without inhibitor) using droplet cell microscopy (DCM). The influence of CeCl3 (250 ppm) addition to the electrolyte is studied through potentiodynamic polarization (DC method). The results suggest that the addition of CeCl3 retards the cathodic reaction rate, thereby decreasing the corrosion rate. This study also highlights on the stability of the system, which is essential to perform local electrochemical impedance spectroscopy (LEIS) using DCM. Fabrication of a proper silicone rubber gasket at the flat capillary tip is important to achieve reproducibility, in order to use DCM in contact mode (as confined droplet). The stability and linearity of the system is proved by sweeping frequencies in both directions and by performing Kramers-Kronig transformation (KKT), respectively. LEIS reveals a charge transfer resistance of 2.83 kΩ cm2 as an effect of inhibitor addition, whereas the charge transfer resistance is 1.9 kΩ cm2 in 0.1 M NaCl solution.

Comparison of accelerated aging of silicone rubber gasket material with aging in a fuel cell environment

AbstractA polymer electrolyte membrane (PEM) fuel cell stack requires gaskets in each cell to keep the reactant gases within their respective regions. Both sealing and electrochemical performance of the fuel cell depend on the long‐term stability of the gasket materials. In this paper, the change in properties and structure of a silicone rubber gasket brought about by use in a fuel cell was studied and compared to the changes in the same silicone rubber gasket material brought about by accelerated aging. The accelerated aging conditions were chosen to relate to the PEM fuel cell environment, but with more extreme conditions of elevated temperature (140°C) and greater acidity. The dilute sulfuric acid accelerated aging solutions used had pH values of 1, 2, and 4. In an additional test, Nafion® membrane suspended in water was used for accelerated aging, to more closely correspond to a PEM fuel cell environment. The analysis showed that acid hydrolysis was the most likely mechanism of degradation and that similar degradation occurred under both real fuel cell and accelerated aging conditions. It was concluded that the accelerated aging test is a good one for rapidly screening materials for resistance to the acidic environment of the fuel cell. ©2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of Thixotropic Agent on the Properties of Conductive Silicone Rubber Gasket for EMI Shielding

In this study, a thixotropic agent was applied to improve the aspect ratio of the silicone rubber gasket and the resulting obtained through modification showed an increase in aspect ratio from 0.26 to 0.91 with the relative to the gasket without thixotropic agent. Compared with the silicone rubber without thixotropic agent, the mechanical properties of the silicone rubber with thixotropic agent were discussed and the results revealed that the shift was very small. In addition, using Ag-coated Cu dendritic powder as conductive fillers, conductive silicone rubber with the resistivity (0.004Ω·cm) was prepared comparable to the relative commercial products can be used for electro-magnetic interference (EMI). The reliability of the conductive composites under aging at 85°C and 85% room humidity (RH) in a temperature/humidity chamber for 48 h was also discussed and the results showed that the shift of the volume resistivity was almost negligible which can meet the actual needs completely.

Effect of the surrounding aeration on microcapillary electrochemical cell experiments

In the microelectrochemical capillary cell technique a silicone rubber gasket is used to avoid any electrolyte leakage between the pulled glass capillary and the working electrode (the metallic tested material). In this study, it is demonstrated that the oxygen reduction reaction (ORR) is strongly affected by the use of the silicone rubber. Experiments under a surrounding argon gas shielding of the pulled capillary in contact with the metallic surface have been performed showing a large effect on the ORR. Considering the high permeation rate of oxygen through silicone, the decrease of the reaction rate observed experimentally was validated by FEM modelling assuming that the air/silicone/water interface at the tip can be described as an air/water interface.

Structural Integrity of Flat Silicon Panels for Nanosatellites: Modeling and Testing

Microsystem interfaces to the macroscopic surroundings and within the microsystems themselves are formidable challenges that this thesis makes an effort to overcome, specifically for enabling a spacecraft based entirely on microsystems. The NanoSpace-1 nanospacecraft is a full-fledged satellite design with mass below 10 kg. The high performance with respect to mass is enabled by a massive implementation of microsystem technology – the entire spacecraft structure is built from square silicon panels that allow for efficient microsystem integration. The panels comprise bonded silicon wafers, fitted with silicone rubber gaskets into aluminium frames. Each module of the spacecraft is added in a way that strengthens and stiffens the overall spacecraft structure. The structural integrity of the silicon module as a generic building block has been successfully proven. The basic design (silicon, silicone, aluminium) survived considerable mechanical loads, where the silicon material contributed significantly to the strength of the structural element. Structural modeling of the silicon building blocks enables rapid iterative design of e.g. spacecraft structures by the use of pertinent model simplifications. Other microsystem interfaces treats fluidic, thermal, and mechanical functions. First, solder sealing of microsystem cavities was demonstrated, using screen-printed solder and localized resistive heating in the microsystem interface. Second, a dismountable fluidic microsystem connector, using a ridged silicon membrane, intended for monopropellant thruster systems, was developed. Third, a thermally regulated microvalve for minute flows, made by a silicon ridge imprint in a stainless steel nipple, was investigated. Finally, particle filters for gas interfaces to microsystems, or between parts of fluidic microsystems, were made from sets of crossed v-grooves in the interface of a bonded silicon wafer stack. Filter manufacture, mass flow and pressure drop characterization, together with numeric modeling for filter design, was performed. All in all this reduces the weight and volume when microsystems are interfaced in their applications.

An aufwuchs chamber slide for high-resolution confocal laser scanning microscopy and stereo imaging of microbial communities in natural biofilms.

Aufwuchs chamber slides were constructed by attaching a silicone rubber gasket to a glass slide with epoxy cement. For biofilm growth, the slides were suspended in Cayuga Lake near Ithaca, NY, for 27 days. Biofilms in the chamber were stained with 0.05% acridine orange. After rinsing, the chamber was filled with molten 1% agarose to stabilize filaments and delicate polymer structures at the biofilm surface. Areas of biofilm approximately 0.5 mm thick on the inner face of the wall of the chamber were selected for side-on optical sectioning in a confocal laser scanning microscope (CLSM). Stacks of high-resolution optical images captured by the CLSM z-sectioning software, were used to create left-right stereo image pairs. At low magnification the stereo pairs showed 3-D details of the microbial landscape in the mature biofilms. Channels, pores, and other structural features of the biofilm matrix were observed in peripheral regions. Higher magnification images revealed the 3-D distribution of specific biofilm components such as filaments of sheathed bacteria projecting outward into the liquid milieu, and organic coatings, including bacterial cells on the surfaces of mineral particles.

12] Microscopy flowcells: Perfusion chambers for real-time study of biofilms

Publisher Summary Flowcells are defined as perfusion chambers for the observation of growth/physiology of stationary cells. Flowcells offer many advantages. A defined, constant environment is provided by laminar flow. They can be made inexpensively and, therefore, can be disposable. As with all methodology, flowcells do have some disadvantages. Sterilization can be difficult because many of the common materials used for flowcell construction do not respond well to autoclaving, especially to repeated autoclaving. In cases of high biomass within the flowcell, it is conceivable that a gradient in nutrients could be established over the length of the flowcell. Flowcells seem to be the best approach for most studies of bacterial biofilms. Flowcells for biofilm microscopy have been built around two designs. The most commonly used design is one in which parallel grooves are milled into a plexiglass base—the grooves stop a few millimeters before the ends of the plexiglass. A second design is one in which the coverslip is used for the top and the bottom of a channel that is formed by a molded silicone rubber gasket.

High-temperature leak-characteristics of PCV hatch flange gasket

Small-model tests were performed to examine the integrity of the containment flange gasket in a severe accident. During a severe accident, containment structures suffer slow pressurization at relatively high temperatures. A realistic understanding of containment performance in such conditions is a major concern in developing an accident management strategy. This paper describes the results of experiments on the sealing capability of flange gaskets at high pressures and high temperatures. Silicone-rubber gaskets, which are used as the sealing material in BWR plant primary containment vessels (PCV) in Japan, were examined in small-model tests. The gaskets show sufficient sealing capability up to 225°C at 20 kgf/cm 2. When applying the leakage characteristics specified in this paper to codes for severe accidents, the results should be examined carefully based on realistic heattransfer phenomena.

Integral heating device for the rose culture chamber.

The culture chamber consists of two metal plates held together by four short screws, a thin (film-type) electrical heating unit, a silicone rubber gasket and two cover slips. The order of assembly is bottom plate, heating element, first cover slip, gasket, second cover slip, and top plate. Syringe needles, one containing a thermistor, and others for supply and removal of fluid are inserted into the chamber through the gasket. Temperature is controlled by electrical connections through a Thermistemp temperature controller.

The use of silicone rubber gaskets for high vacuum work

The use of silicone rubber gaskets for high vacuum work