Seal Applications Research Articles

Effect of Post-space Preparation with Rotary Devices and Heated Instruments on Microbial Leakage of Gutta-percha and Resilon-Epiphany Obturated Canals

Introduction: After endodontic procedures, root canal reinfection is a main concern for dentists. However, application of a proper apical seal can prevent such contamination. Therefore, it seems necessary to study the factors affecting the development of a suitable apical seal. Materials and Methods: In this study, 64 extracted human single-canal premolars were used. An equal length of roots was obtained by cutting the crown. The teeth were randomly divided into four experimental groups of 15 premolars, as well as 2 positive and negative controls. The root canal was manually prepared using K-file and step back method through canal filling by lateral compaction technique. In GP and GH groups, gutta-percha and AH 26 sealer were used to fill the canals, while Resilon and Epiphany sealer were used in RP and RH groups, respectively. Then, to prepare the post space, Peeso Reamer drill was used in GP and RP groups while heat carrier was applied in GH and RH groups to prepare the post space, respectively. The coronal part of each root was contacted with enterococcus faecalis leachate in BHI medium and the root end was placed in the same culture medium. The samples were daily checked for turbidity in the lower culture medium for 90 days. The average duration of bacterial leakage between the groups wascompared using independent Student t-test. Results: All the positive control samples showed bacterial infiltration within 24 to 48 hours, while the negative control teeth remained uninfected during the test. Comparison of bacterial leakage rates between GP and GH groups showed no significant difference, which was similar to comparison results between RP and RH groups (P=0.549 and P=0.097, respectively). Comparison of bacterial leakage between GP and RP groups, as well as between GH and RH groups, showed a significant difference (P=0.018 and P<0.001, respectively), so that the average duration of leakage was significantly longer in the teeth obturated with gutta-percha/AH26 than with Resilon/Epiphany. There was a significant difference in root canal filler material regardless of the post space development method, i.e. heat carrier and Peeso Reamer (P<0.001). Conclusion: Considering the results of this study, the use of gutta-percha as a root filling material results in a better apical seal than Resilon. Application of heat carrier and Peeso Reamer showed no significant difference in effectiveness on the apical seal.

Studies on the mechanical properties of carbon black-halloysite nanotube hybrid fillers in nitrile PVC nanocomposites for oil seal applications

The International Scientific Research Organization for Science, Engineering and Technology (ISROSET) is a Non-Profit Organization; The ISROSET is dedicated to improvement in academic sectors of Science (Chemistry, Bio-chemistry, Zoology, Botany, Biotechnology, Pharmaceutical Science, Bioscience, Bioinformatics, Biometrics, Biostatistics, Microbiology, Environmental Management, Medical Science, Forensic Science, Home Science, Library Science, Material Science Military Science, Physical Science, Physical Education Science, Educational Science, Fisheries, seed technology, Agriculture, Forestry Science, Mathematics, Physics, Statistics and Geology/Earth Science), Computer Science, Engineering and Information Technology, Commerce, Management, Economics Sociology and Social Science.

Experimental Study on Performances of Carbon Seal and Finger Seal under High-speed and High-pressure Condition

Carbon seal and finger seal are both advanced and used in aero-engine and gas turbine. Compared with the finger seal, the application of carbon seal is longer and its technology is more mature. But the finger seal also has excellent sealing performance, and it is much more economical than carbon seal. Based on a self-developed dynamic sealing test rig, the experimental studies on performances of carbon seal and finger seal under high-speed and high-pressure conditions are carried out in this paper, and the comparison on leakage and durability of the two seals is carried out in-depth to find the possibility that replacing carbon seal with finger seal, which can provide references for the selection of sealing types. The experimental results show that, under the same structural and operating conditions, the durability of carbon seal is better than that of the metal matrix finger seal, but the leakage of finger seal is smaller. Considering the manufacturing costs, the finger seal has potential to replace carbon seal at lower speed. Therefore, developing nonmetallic finger seal is an effective way to promote advanced sealing technology, which combines the flexible structure of finger seal with new material that has high thermal conductivity, low expansion, and low friction.

Effects of grooved ring rotation and working fluid on the performance of dry gas seal

The thermal-fluid-structure interaction coupling method is adopted in this paper to analyze the sealing performance of spiral-grooved dry gas seal. Effect of grooved ring rotation on sealing performance is discussed in detail. The real gas model is applied to obtain the accurate sealing performance under different inlet temperature and pressure with air and SCO2 as working fluid respectively, which provides a vital reference for SCO2 seal application. The results obtained with the thermal-fluid-structure interaction coupling method are reliable. It is found that grooved ring rotation has a significant influence on sealing performance especially for large film thickness. The pressure and temperature of the model which is grooved on the rotating ring are higher than those of the model which is grooved on the stationary ring, but the open force and leakage are opposite. In addition, SCO2 model and air model show a significant difference on the sealing performance and the sealing performance of SCO2 model is easier to be affected by the inlet temperature and pressure compared with air model.

Tribological properties of carbon nanotube as co-reinforcing additive in carbon black/acrylonitrile butadiene rubber composites for hydraulic seal applications

This work investigated the cure characteristic, physical mechanical properties, and tribology behavior of carbon black filled acrylonitrile butadiene rubber composites using multi-walled carbon nanotubes as co-reinforcing additive in various contents from 0, 3, 6, 9, and 15 parts per hundred rubbers. The physical and tribological behavior was also observed in large-scale piston driven hydraulic apparatus which was specially designed for seal applications. The results suggested that the modulus and hardness were found to increase after adding multi-walled carbon nanotube whereas the tensile and tear strength were not significantly affected. Adding multi-walled carbon nanotube was found to increase the bound rubber and crosslink density. For ball-on-disc tribo-testing, it was found that the coefficient of friction of the rubber composites decreased with multi-walled carbon nanotube content and the applied loads whereas the specific wear rate was more influenced by the applied loads used. Finally, under the large-scale piston driven hydraulic test apparatus in comparison with commercial grade rubber seals, it was found that the weight loss for the acrylonitrile butadiene rubber composites with multi-walled carbon nanotube was much lower than that without multi-walled carbon nanotube. The carbon black/acrylonitrile butadiene rubber composites with 9–12 parts per hundred rubbers multi-walled carbon nanotube were recommended as the most suitable for hydraulic seal applications.

Weight Reduction Study on BIW by Using Boron Alloyed Hot Stamping Solution of Front Frame Rail Instead Conventional HSS or AHSS Applications

With the increase of the performance requirements and homologative restrictions the correct way of choosing the right material on the related area is an inevitable manner for weight reduction of the vehicles. A hot stamped front frame rail which have roughly same performance with conventional cold stamped one was designed by using tailor welded and patch reinforcement. The part was optimized with full sized frontal crash (EUNCAP), full sized rear crash (Trias33) and fatigue simulations. Critic interferences-accelerations into the passenger cabin was considered for acceptance criteria of frontal crash, deformations on fuel system for acceptance criteria of rear crash and plastic deformations on the part, especially suspension fixing points, for acceptance criteria of fatigue test. At the end of all optimization the thicknesses of the system was designed as; first tailor welded part: 1.2mm, second tailor welded part:2.5mm and patch reinforcement: 1mm. Also some design critics (such as laser cut holes and trims, seal and barrier application for eliminating water infiltration into the bare surfaces of the hot stamped part) was clarified to guarantee the performance of the part during lifecycle of the vehicle. With final condition new hot stamped system was weighted 5 kg and gained a 2 kg weight reduction.

Degradation of blending vulcanized natural rubber and nitril rubber (NR/NBR) by dimethyl ether through variation of elastomer ratio

Dimethyl ether can cause degradation of the rubber material seal in some applications. In order to use of natural rubber in industry, research about a blending of natural rubber (NR) and nitrile rubber (NBR) to produce rubber to meet the standard seal material application were conducted. This study will observe the degradation mechanisms that occur in the blending natural rubber and nitrile rubber (NR/NBR) by dimethyl ether. Nitrile rubber types used in this study is medium quality nitrile rubber with 33% of acrylonitrile content (NBR33). The observed parameters are percent change in mass, mechanical properties and surface morphology. This study is limited to see the effect of variation vulcanized blending ratio (NR/NBR33) against to swelling. The increase of nitrile rubber (NBR33) ratio of blending rubber vulcanized can reduce the tensile strength and elongation. The best elastomer variation was obtained after comparing with the standard feasibility material of seal is rubber vulcanized blending (NR/NBR33) with ratio 40:60 NR: NBR.

Evaluation of significant factors for aggregate retention in chip seals based on mesostructured finite element model

The retention of aggregates or chips on chip seal is critical for the durability of chip seal application in pavement maintenance. Most evaluation on aggregate retention have focused on laboratory experiment regarding asphalt-aggregate bonding, however, there are many other factors that are needed to be investigated as a whole picture. As such, this paper presents a mechanistic point view of understanding the effects on the aggregate retention based on a two-dimensional finite element model of aggregate-asphalt interface. The horizontal strain and shear strain in the interface are evaluated in terms of six factors including asphalt type, temperature, loading level, horizontal loading, aggregate shape, and interface bonding conditions. The analysis of variance (ANOVA) of influencing factors for critical response is further conducted. The results show that shear strain is more significant than the horizontal strain, which should be taken as an evaluation index for aggregate retention in chip seal. The influence of six factors on the shear strain of aggregate-asphalt interface is highly significant. The greatest significant influence is temperature, followed by horizontal loading, asphalt type, loads, aggregate shape, and interface bonding conditions. The results of this study provides a mechanistic viewpoint for chip seal designer to consider varying conditions for ensuring aggregate retention in chip seal.

FRACTIONAL FACTORIAL DOE PLANNING TO REDUCE INTERNAL REJECTIONS ON LEAK TEST OF A COMBUSTION ENGINE PRODUCTION LINE

This work was applied in automotive industry in order to improve the efficiency of the combustion engines production leak test by using a fraction factorial DOE (Design of Experiments). The application of the anaerobic seal is done by a robot dispenser, and the main goal of this work is to demonstrate the application of fraction factorial DOE to improve the inputs of the application and eliminate leak fails on production leak test on the combustion engines at “T-joint” from the intersection between cylinder head, valve cover gasket and front cap. The method applied is experiment and the software used to plan the DOE and analyze the collected data is the Minitab. The inputs considered by the team application were four as: hose temperature, panel temperature, robot tip distance, and robot speed, as a result the input with the most significant effect identified on the DOE analysis is the robot tip distance. The outcome is zero leak engine on the “T-joint” at leak test, and then it was decided to evaluate two outputs: 1 - leak rate on leak test – this output showed no significance when analyzed the results from the DOE because it does not consider noise factors as environment temperature and humidity; 2 – seal bead diameter – this output showed to be significance on DOE, and is directly related to the root cause, because the engines failed with leak on production leak test are missing or with lack of anaerobic seal on the “T-joint”. The main result of this fractional factorial DOE is the best set of input parameters which exceeded the target of 80% improvement and achieved zero leak on the “T-joint” between cylinder head, valve cover gasket and front cap. This shows that fractional factorial DOE is an efficient method to be applied on the industry to improve process.

EPDM Developments for Automotive Sealing Applications via Advanced Molecular Catalyst (AMC) Technology

EPDM Developments for Automotive Sealing Applications via Advanced Molecular Catalyst (AMC) Technology

Effective surface treatment techniques for refinishing oil-stained road surface

Oil spillage on pavement surface is a hazard for all road users as it causes road slipperiness. Although there are various applications of oil removers for cleanup of oil spillages, many of which would require time-consuming treatment, no research has been conducted to develop temporary and fast road resurfacing technique which can be completed within a short time (1–2 h). The objective of this research is to develop a fast-setting asphalt surface treatment to respond to oil spillages on roads so as to allow resumption of traffic movements, for up to 2 days before surface rejuvenation. A series of surface treatments were selected for experimentation based on the consideration of ease of application and effectiveness to satisfy the road performance requirements. A tack coat of CRS-2 asphalt emulsion with chip seal coating was applied to refinish the oil-spilled dense- and open-graded specimens. The oil types were diesel, hydraulic oil, engine oil, and cooking oil. A British pendulum skid resistance tester was used to measure the skid resistance of the treated surfaces. The results show that using a tack coat with chip seal (CRS-2) applications to refinish the oil-spilled road can be completed within 1–1½ h. With adequate skid resistance performance, chip seal (CRS-2) application is a promising method to refinish oil-spilled road for all types of oil. A tack coat (CRS-2) application may be an option for the practitioner to use as a surface treatment to remedy oil spillage on dense-graded specimens, while asphalt emulsion alone shall not work well for oil spillage on open-graded specimens. PosiTest (pull-off tester) was carried out to determine the pull-off tensile strength of the applied surface layers, i.e., chip seal from the pavement surface. The results show that chip seal treated specimen with pre-wash yields higher pull-off tensile strength than chip seal treated specimen without pre-wash.

Prediction of Electrochemical Performance of Lower Temperature Operating Na-NiCl2 Battery

Sodium nickel chloride (Na-NiCl2) batteries are gaining growing attentions as a strong potential contender for advanced electric vehicle (EV) and stationary energy storage system (ESS) applications. The cathode compartment of a Na-NiCl2 battery features by a mixture of solid NaCl and Ni granules impregnated with a liquid NaAlCl4 catholyte. During charge-discharge cycles, complicated electrochemical reactions take place, including transportation of Na+ ions through NaAlCl4 catholyte, the dissolution/coarsening of NaCl particles, formation/decomposition of NiCl2 layers on the active Ni surface, and electron transport through the Ni granules. We are developing advanced Na-NiCl2 batteries that operate at relatively lower temperatures of below 200 °C to minimize its cell degradation typically observed at high operation temperature (over ~270 °C) and to enable application of simple and cheaper polymer seals for cell manufacturing. However, the diffusion and the ionic migration kinetics of active Na+ ions are restricted at the lower temperatures that may limit cell performance. In this presentation, we introduce a multi-physics continuum computational model to capture the electrochemical behaviors of planar lower temperature Na-NiCl2 batteries. The computational results will elucidate impacts of (i) cell operation temperatures, (ii) current densities, and (iii) cathode dimensions on the electrochemical performance of prototype planar Na-NiCl2 cells. The developed prediction model is expected to provide a useful guideline for the experimental fabrication of advanced Na-NiCl2 batteries with maximized cell performance at relatively lower temperatures.

Fretting wear behaviors of acrylonitrile-butadiene rubber (NBR) against diamond-like carbon and graphene coatings

The study focuses on understanding how to govern the fretting wear behaviors under dry lubricated contact to find out the keys to develop new coatings for rubber seal applications. Fretting wear behaviors of acrylonitrile-butadiene rubber (NBR) against steel substrate, diamond-like carbon, and graphene coatings were comparatively investigated under dry conditions. Dynamic analyses were performed in combination with examinations through scanning electron microscopy (SEM), 3D surface profilometry, and X-ray photoelectron spectroscopy (XPS). Experimental results show that, there was significant difference between the fretting running regime for graphene coating and the fretting running regimes for diamond-like carbon (DLC) coating and steel substrate; the mixed fretting regime (MFR) disappeared and the boundary between the partial slip regime (PSR) and the slip regime (SR) shifted to the direction of smaller amplitude displacement in running condition fretting map (RCFM). Moreover, it had excellent anti-friction and wear-resistant performances under fretting condition. However, the fretting running behaviors of the DLC coating are similar to those of the steel substrate, so the DLC coating could not migrate the fretting running regimes effectively. The damage on all the tribopairs in partial slip regime was very slight and the adhesion was the main damage mechanism for the DLC coating and the steel substrate in the MFR and SR. The sticky layers on the worn surface played an important role. For the graphene coating, no obvious damage could be observed on the tribopairs. Therefore, the graphene coating exhibited widely potential applications for alleviating fretting wear.

A (in)eficácia dos selos verdes sobre o comportamento dos consumidores: um estudo experimental

The objective of the study was to analyze consumers' perceptions about green seals, according to how well known these seals are and to their own profile of green consumption. Therefore, a theoretical reference was made on sustainable consumption, as well as on the application of green seals in the perspective of green marketing. The method adopted was a hypothetical-deductive approach, carried out through two experiments (one online and the other face-to-face), both with factorial design 2 (true and well-known green seal versus false seal and nothing known) x 2 very sustainable versus low sustainable consumer profile). In view of the results obtained, four main discussions could be made, such as the possibility of greenwashing due to the clear mention of environmental aspects, either in relation to the seal itself or to the statements underlying it, the ineffectiveness of adopting green seals and influence of this ineffectiveness even in consumers who reported having a more sustainable consumption profile.

Development of Compact Hydraulic Positive Displacement Motor Featuring No Rotor Vibrations in Well Drilling

Background/Objectives: The objective of this study is to develop a new compact hydraulic positive displacement motor that would operate without rotor vibrations. Methods: Assisted by 3D printers, the models of the new hydraulic machines have been developed. The results of the laboratory and bench testing confirmed the relevance of the selected area of investigations. Findings: The results of the calculations and the laboratory tests of the models of the hydraulic machines showed that upon introducing some constructive adjustments such class of machines can be used for developing new compact hydraulic positive displacement motors that would operate with no rotor vibrations in the process of drilling oil wells. The major objective of the undertaken investigations is to create the new and more efficient sealing that is supposed to be installed between the cylindrical rotor and cylindrical stator in the hydraulic machine. The novelty of the structure rests with the application of a partitioning seal where separate sections of the seal are installed consecutively along the screw line. Thereat, the design of the new machine avoids using any screw surfaces and applies only flat or cylindrical surfaces. The results of the undertaken scientific and design activities can also be used for developing hydraulic machines in other industries that set strict regulations on the vibration levels, on the weight and dimensions of the process equipment. Applications/Improvements: Principal area of applying the new design is related to drilling downward and horizontal oil and gas wells. Compact motor can be used for the repairs at the oil wells.

Alternative Metallurgies for MEMS Lid Seal

Abstract MEMS devices are a segment of the electronics industry enjoying explosive growth. With the advent of the internet of things (IoT), the trajectory for growth will continue to be steep and price pressures on both the devices and packaging will be intense. Current MEMS packaging schemes rely heavily on an architecture that employs a metal-can or laminate “lid” attached to the device package with a solder ring. This ring serves to connect the package elements together mechanically and to protect the device from noise (electronic or acoustic) and environmental damage. Like most modern electronic devices, MEMS devices are subject to the challenges imposed by the requirement for lead-free packaging. As with many devices, solder connections formed within the package have a similar composition, and therefore a similar reflow profile, to the solder used to attach the packaged components to a substrate. Devices that yield well at the manufacturer are thus susceptible to field failure at the assembly site induced by remelting of the solder within the package during assembly reflow. Unlike in SIP packages where the solder joints in the module are often encased in mold compound, the ring seal in MEMS devices is exposed and unreinforced resulting in failures such as lid shift, solder flow or flux contamination in the device cavity, and package deconstruction - particularly during rework. These type of post-fabrication yield losses can be very costly. Transient liquid phase (TLPS) sintering paste compositions are a new class of solder replacement materials that can be processed at typical reflow temperatures, but which do not remelt when subjected to subsequent thermal excursions. TLPS pastes combine solder alloy particles and reactive metal particles in proportions such that the solder ‘thermosets’ during a typical solder reflow cycle. This ‘thermosetting’ behavior results in a joint that does not remelt at the original reflow temperature, and thus enables the highly reliable electrical interconnect essential for assemblies that will undergo subsequent reflow excursions. TLPS pastes are similar to solders in many respects. The electrical, thermal and mechanical performance is similar to conventionally used tin-based solders. The TLPS pastes are stored and applied like solder pastes. The reflow cycles used to form the TLPS paste joints are also similar to those for forming solder joints. However, unlike solder, TLPS materials do not change shape during reflow or wet substrates beyond the deposition footprint. Also unlike solder, the metals within the bulk of the TLPS interconnect react with one another resulting in a stable interconnect with a thermally robust bonding structure to joining surfaces, even after subsequent thermal cycles. These attributes present both unique opportunities and unique challenges for addressing MEMS lid seal applications. This paper will explore the key material and engineering challenges for implementation of TLPS paste in MEMS lid seal applications.

Experimental Air-Tightness Analysis in Mediterranean Buildings after Windows Retrofit

Energy saving and Indoor Air Quality (IAQ) in buildings are strongly affected by air leakages. Several studies reveal that the energy loss owing to leaky windows can account for up to 40% of the total building energy demand. Furthermore, at the design stage, the possible infiltration of outdoor air through windows is not taken into account when determining the nominal outdoor airflow rate of the ventilation system. This practice may result in an oversizing of the ventilation system and consequent energy waste. Thus, the air-tightness class of a wall assembly should be assessed for each window component considering the type of material, the presence of the seal, the type of closure, the sealing and the maintenance condition. In this paper, the authors present the experimental results of air-tightness measurements carried out using the fan pressurization method in three residential buildings located in the Mediterranean region before and after a window retrofit. Two different window retrofits were investigated: the application of rubber seals on window frames and the substitution of existing windows with new certified high performance windows. The effectiveness of such retrofits was estimated also in terms of energy saving. Test results demonstrated a high variability of the building air tightness after window retrofits, despite the fact that air tight–certified windows were used.

Influence of microstructure in nitrile polymer on curing characteristics and mechanical properties of carbon black-filled rubber composite for seal applications

Acrylonitrile butadiene rubber (NBR) is widely used in seal applications due to its excellent oil resistance. In this article, carbon black-filled NBR composites, which differed in their acrylonitrile (ACN) and butadiene content ratios, were prepared and their curing characteristics and mechanical properties were investigated. Curing characteristics were investigated by measuring chemical kinetics and onset temperature of cross-linking reaction. Cross-linking density was measured by the volume swelling test. Mechanical properties, oil resistance, and compression set (CS) tests were also conducted. From these results, it was found that the microstructure in NBR polymer is closely connected to the curing characteristics and mechanical properties of the composite. On increasing the ACN content, Shore A hardness, tensile strength at break, elongation at break, oil resistance, and CS were raised, while, on the other hand cross-linking density, kinetics of cross-linking reaction, and bound rubber content were decreased.

Tribological Performance of Polyamide-Imide Seal Ring Under Seawater Lubrication

High-performance engineering polymers are potential candidate materials for mechanical seals, especially in corrosive environments and environments where substantial shock and vibration loads are present. This study addresses the friction and wear performances of polyamide-imide (PAI) sliding against tungsten carbide (WC) in seawater for seal applications. The experimental setup consists of two nominally flat rings rotating against each other to simulate the contact in mechanical seals. Three types of experiments were performed, i.e., measurement of friction and wear in a series of 8-h tests, measurement of the friction coefficient as a function of speed and load and measurement of PV (pressure times velocity) limit. Test results show that at lightly loaded conditions WC/PAI seal rings in seawater can reach hydrodynamic lubrication with ultra-low friction coefficient and wear rate.

Experience in Rehabilitation of Low-volume Roads Using Soft Asphalt and Otta Seal Technologies

In Lithuania more than third (33.9%) of state roads are gravel roads. Maintenance of these roads needs large budget and operation of them results in social discomfort. The best method to improve driving conditions and avoid social discomfort for the inhabitants living close to gravel roads is to reduce dustiness using suppressants or even construct asphalt pavement. But, dust suppressants are not enough efficient due to wet and rainy climate in Lithuania. Also, the performance of conventional asphalt pavement used for low-volume roads was unsatisfactory, due to thin frost resistance layer or weak subgrade. And those additional works significantly increase road construction costs up to 25%.As alternative solution the use of soft asphalt and Otta Seal technologies were proposed. Therefore, in 2012 the trial sections were constructed in order to clarify the effectiveness and functionality of soft asphalt and Otta Seal technologies under current traffic and climate conditions. Measurements of roughness and condition of soft asphalt pavement and Otta Seal were carried out in spring, summer (only condition of soft asphalt pavement) and autumn every year. The average roughness of all the trial sections with soft asphalt pavement or most of the trial sections with double Otta Seal complies with the requirements (≤ 3.5 m/km) to the roads of regional significance. Besides, the roughness of the trial sections with soft asphalt is similar to that of the sections with asphalt base course-pavement. Trial road sections with soft asphalt pavement are in good condition after 30–32 months of operation, and longitudinal cracks were observed as the main defect, which tends to heal in summer period. The Otta Seal also represented the ability to self-heal under high pavement temperature. However, the condition of trial sections with Otta Seal were not as good as soft asphalt pavement. The formation of the most defects were identified as causes of inappropriate amount of binder, insufficient maintenance in summer period and unqualified procedure of applying Otta Seal. Based on the results of this research the conclusions and recommendations were made for further application of soft asphalt and Otta Seal in Lithuania.