Stainless Steel Piston Research Articles

Speech intelligibility prediction based on a physiological model of the human ear and a hierarchical spiking neural network.

A speech intelligibility (SI) prediction model is proposed that includes an auditory preprocessing component based on the physiological anatomy and activity of the human ear, a hierarchical spiking neural network, and a decision back-end processing based on correlation analysis. The auditory preprocessing component effectively captures advanced physiological details of the auditory system, such as retrograde traveling waves, longitudinal coupling, and cochlear nonlinearity. The ability of the model to predict data from normal-hearing listeners under various additive noise conditions was considered. The predictions closely matched the experimental test data under all conditions. Furthermore, we developed a lumped mass model of a McGee stainless-steel piston with the middle-ear to study the recovery of individuals with otosclerosis. We show that the proposed SI model accurately simulates the effect of middle-ear intervention on SI. Consequently, the model establishes a model-based relationship between objective measures of human ear damage, like distortion product otoacoustic emissions, and speech perception. Moreover, the SI model can serve as a robust tool for optimizing parameters and for preoperative assessment of artificial stimuli, providing a valuable reference for clinical treatments of conductive hearing loss.

Conventional-, bulk-fill- or flowable-resin composites as prosthetic core build-up: Influence on the load-bearing capacity under fatigue of bonded leucite-reinforced glass-ceramic

This study aimed to evaluate the fatigue performance of simplified ceramic restorations (leucite-reinforced glass ceramic) adhesively cemented onto substrates of different resin composites. Three options from the same commercial line were selected (Tetric N-Line, Ivoclar), classified as Conventional (CRC), Bulk-fill (BRC) and Flowable (FRC), which were used to make discs using a cylindrical metallic device (n = 19; Ø = 10 mm, thickness = 2.0 mm). A total of 57 discs (Ø = 10 mm, thickness = 1.0 mm) were made from CAD/CAM prefabricated blocks of a leucite reinforced glass-ceramic (Empress CAD, Ivoclar) to simulate a monolithic restoration, then were randomly distributed to be bonded on 19 discs of each three different resin composite substrates (CRC; BRC; or FRC) with a dual resin cement (Multilink N; Ivoclar). The samples were subjected to a compression test with a hemispherical stainless-steel piston (Ø = 40 mm) at a monotonic regimen (n = 4; 1 mm/min loading rate and 500 kgf loading cell until fracture). The cyclic fatigue test was performed underwater at a frequency of 20 Hz (n = 15). The first step was applied using 200N for 5000 cycles, followed by increments of 50N at each step of 10,000 until failure. The outcome considered for both tests was the occurrence of radial crack. Specific statistical tests (α = 0.05) were performed for monotonic (One-way ANOVA; Tukey's test) and fatigue data (Kaplan-Meier test; Log-rank test). Fractography of fractured samples were also performed. The FRC group had the lowest failure load in both test regimes (p < 0.05; monotonic: 726.64N; fatigue: 716.67N). There were no differences between the CRC and BRC groups (p > 0.05; monotonic: 989.30 and 990.11N; fatigue: 810.00 and 833.33N, respectively). The same result was obtained considering cycles for fatigue failure (FRC < CRC=BRC). Leucite glass-ceramic bonded to substrates made of flowable resin composite behaves worse mechanically than bonding to conventional or bulk-fill resin composite substrates.

Design, manufacturing, and testing of a laser textured piston ring surface reinforced with a CuCoBe–diamond composite by hot-pressing

A CuCoBe–diamond composite was used to reinforce a laser textured 410 stainless steel piston ring by hot-pressing. Different hot-pressing parameters were used to optimize the sintering process of the CuCoBe particles (P = 25 and 50 MPa, T = 820 and 980 °C, and t = 15 and 30 min). The results showed an increase in the hardness of the hot-pressed samples (50.5% and 48.5% for P = 25 and 50 MPa, respectively). Three textures with different track widths and distances between them were produced by laser on the compression piston rings’ surface. The composite powders were used for the reinforcement of the textures by hot-pressing at the optimized sintering parameters (T = 980 °C, P = 25 and 50 MPa, and t = 15 min). The tribological results revealed that larger texture dimensions led to enhanced tribological performance.

Inspection for Precision Alignment of the piston Assembly used in the Upgradation of a Diesel Fired Engine Aimed for Increasing Efficiency

In this research work, it is proposed to reduce the fuel consumption of a diesel engine. The proposal aims on adding a stainless steel piston over the aluminium conventional piston through a piston rod. Firing takes place over the stainless steel piston. Between stainless steel piston and cylinder small gap only is maintained without physical contact and liquid lubrication is totally avoided. The expected overall efficiency improvement is 30% to 40%, as air-cooling totally avoided and this requires less fuel to be burnt. Here the dual piston needs to be perfectly aligned and hence an inspection procedure was thought of and the results arrived at are analyzed and concluded. The maximum misalignment of top cylinder piston axis found to be 12.5 microns and maximum out of cylindricity over outer diameter found to be 25 microns

Thermal Performance Analysis for a Remodified Diesel Engine to Improve Fuel Efficiency

Heavy trucks, buses, lorries, and other vehicles require over Rs. 4 lakh crores of diesel each year, which is imported at a cost of approximately Rs. 5 lakh crores annually. These cars' engines use water cooling, which keeps the internal engine components below 100°C.For the following reasons, the material temperature is kept below 100°C. The water in the radiator will boil if the cylinder temperature exceeds 100°C. The liquid lubricant burns and becomes sticky over 140°C, which causes the engine to seize. As a result, the need for a liquid lubricant, the need to cool the radiator and engine cylinders, and the loss of 35 to 40% of the heat equivalent of the diesel can all be avoided. In order to accomplish this, a second stainless steel cylinder is added above the existing conventional engine cylinder. A stainless steel piston then glides inside the stainless steel cylinder, maintaining a very small clearance and requiring no lubrication. A stainless steel piston rod guided by bearings connects the stainless steel piston to the traditional engine piston, and the two pistons reciprocate as a single unit. The traditional cylinder and piston are now just utilized to guide the piston assembly and bearings; the firing has been relocated to a stainless steel cylinder. As a result, the engine's heat flow will be reduced, increasing efficiency. As a result, the radiator is turned off because the traditional cylinder isn't burning, saving 35 to 40 percent of the gasoline that would have been lost to heat dissipation through the radiator. As a result, improving the efficiency of all large trucks could save up to 40 to 50% of the diesel used by large trucks, as well as 1.5 to 2 lakh crores of rupees per year, making this research of national significance

Thermomechanical Treatment of Stainless Steel Piston Rings

Thermomechanical Treatment of Stainless Steel Piston Rings

Development of a Thermomechanical Treatment Mode for Stainless-Steel Rings.

This article describes a technology for the thermomechanical treatment of stainless-steel piston rings. This technology makes it possible to obtain rings with an optimal combination of plastic and strength properties that is essential for piston rings. The following thermomechanical treatment is suggested for piston rings manufacturing: quenching at 1050 °C, holding for 30 min and cooling in water, then straining by the HPT method for eight cycles at cryogenic temperature and annealing at a temperature up to 600 °C. The resulting microstructure consisted of fine austenite grains sized 0.3 μm and evenly distributed carbide particles. Annealing above this temperature led to the formation of ferrite in the structure; however, preserving the maximum fraction of austenitic component is very important, since the reduction of austenite in the structure will cause a deterioration of corrosion resistance. The strength properties of steel after such treatment increased by almost two times compared with the initial ones: microhardness increased from 980 MPa to 2425 MPa, relative elongation increased by 20%. The proposed technology will improve the strength and performance characteristics of piston rings, as well as increase their service life, which will lead to significant savings in the cost of repair, replacement and downtime.

Comparative study between Teflon and Robinson stainless steel Prostheses in ototsclerosis surgery

BACKGROUND: The main cause of conductive hearing loss in the presence of a completely normal tympanic membrane is otosclerosis. There are different types of prostheses that could be used in the operation with different materials, designs, and shapes. The prostheses utilized in this study including both Teflon and Robinson are assessed. The aim of our work is to match and determine the surgical steps, postoperative results, and surgical complications of both Teflon piston and Robinson titanium prosthesis in line with the improvement in hearing and therefore the ability to decrease the air-bone gap.Results: stapedotomy done for 40 patients with Teflon piston and Robinson stainless steel piston prosthesis, 20 patients for each type. Both groups were matched based on age and preoperative bone-conduction scores. Follow up for all patients were done up to 6 months postoperatively. We have excluded all revision cases. A comparison between both prostheses was assessed by differences in the Air Bone (AB) Gap and surgical difficulties and complications. Both groups showed no significant difference either in hearing improvement or postoperative decrease of an air-bone gap. The Robison titanium piston needs more surgical skills than Teflon one. Both groups had no surgical complications.Conclusions: There is an equal benefit to patients with the use either of Teflon piston or Robinson protheses and there is no statistically significant difference between both of them. We need a long time of follow up the results to be analyzed.Keywords: Teflon prosthesis, Robinson prostheses, otosclerosis, stapedectomy.

Tribological Properties of Coated and Uncoated Materials for Piston Ring Applications

Coating is an essential method to improve surface properties such as corrosion resistance, lubrication of material used. The simulated laboratory tests is a more feasible alternative to experimental or real-time testing. A study conducted under controlled parameters of load, surface coating, and temperature showed the changes in the tribological characteristics with and without functionally graded cermet coatings and their influence on stainless-steel piston rings. Altogether simulations for six cycles were taken into consideration for each of the test cases - with and without coating. The obtained data from the microstructure imaging in optical microscope following the investigation conducted employing tribometer showed that the resistance of the coated rings was comparatively more than the uncoated rings, hence proving the coating to be beneficial for real-time use.

Failure analysis of AISI 410 stainless-steel piston rod in spillway floodgate

Abstract We investigate the causes of failure of a piston rod of a hydraulic cylinder, which moves a spillway floodgate of a hydroelectric power plant, after 30 years of service. The fractured piston rod is made of the AISI 410 martensitic stainless steel (condition T). The analysis shows that intergranular cracking originated on the outer surface and propagated along prior austenite grain boundaries, accompanied by corrosive attacks between martensite needles. The low performance of the piston rod can be explained by the improper heat treatment during the manufacturing process, which led to a high δ-ferrite content, temper embrittlement, low toughness, and susceptibility to stress corrosion cracking.

How does hydrofluoric acid etching affect the cyclic load-to-failure of lithium disilicate restorations?

This study investigated the effect of etching with distinct hydrofluoric (HF) acid concentrations on the cyclic load-to-failure (CLf) of simplified lithium disilicate glass-ceramic restorations adhesively cemented to a dentin analogue (n = 20): non-etched/control (CTRL), or etched for 20 s with HF acid at 3% (HF3), 5% (HF5), or 10% (HF10). A silane coating was then applied onto the ceramic surfaces. Fatigue tests followed the staircase approach (initial load= 720 N; step-size= 70 N; 500,000 cycles per sample; 20 Hz) using a hemispheric stainless-steel piston (Ø= 40 mm) under water. The CLf data were analyzed using Dixon and Mood method. Topographic and fractographic analyses were conducted. CLf (in N) of HF3 (1355 ± 32.0) and HF5 (1335 ± 58.8) groups were the highest and statistically similar; HF10 presented intermediate CLf (1175 ± 132.9), while the non-etched group had the lowest one (965 ± 145.0). Topographical analysis showed that the higher the HF acid concentration, the more pronounced the topographical changes. All failures (radial cracks) started from the inner surface of the ceramic discs. Topographical changes promoted by intermediate HF acid concentrations (3% and 5%) may improve fatigue performance for adhesively-cemented lithium disilicate restorations.

Hydrofluoric acid concentrations: Effect on the cyclic load-to-failure of machined lithium disilicate restorations

ObjectivesTo evaluate the effects of the etching with different hydrofluoric acid (HF) concentrations on the cyclic load-to-failure (CLf) of machined lithium disilicate crowns cemented to dentin analogue material. MethodsPairs of dentin analogue prosthetic preparations and lithium disilicate ceramic crowns with simplified and standardized designs were machined (n=18). The preparations were etched with 10% HF (60s), followed by primer application. The intaglio surface of the ceramic crowns was treated as follows: non-etched (control, CTRL); or etched for 20s with different HF concentrations — 3% (HF3), or 5% (HF5), or 10% (HF10). A silane coating was then applied onto the treated ceramic surfaces, and they were adhesively cemented to the preparations. To perform the fatigue tests (staircase approach), a hemispheric stainless-steel piston (Ø=40mm) applied cyclic loads in the center of the crowns under water (initial load: 720N; step-size: 70N; cycles: 500,000; frequency: 20Hz). Additionally, topographic, fractographic, and fractal analyses were carried out. The fatigue data were analyzed using the Dixon and Mood method. ResultsAlthough the topographic and fractal analyses depicted the action of HF etching altering the superficial complexity and topography, the preponderant topography pattern was established by machining on CAD/CAM. All groups showed similar CLf (in N) (CTRL=805.00±91.23; HF3=781.25±29.87; HF5=755.00±154.49; HF10=833.75±100.74). SignificanceEtching with different HF acid concentrations did not promote a deleterious effect on the cyclic load-to-failure of machined lithium disilicate crowns.

Fatigue failure load of two resin-bonded zirconia-reinforced lithium silicate glass-ceramics: Effect of ceramic thickness

ObjectivesTo evaluate the effect of ceramic thickness on the fatigue failure load of two zirconia-reinforced lithium silicate (ZLS) glass-ceramics, adhesively cemented to a dentin analogue material. MethodsDisc-shaped specimens were allocated into 8 groups (n=25) considering two study factors: ZLS ceramic type (Vita Suprinity — VS; and Celtra Duo — CD), and ceramic thickness (1.0; 1.5; 2.0; and 2.5mm). A trilayer assembly (ϕ=10mm; thickness=3.5mm) was designed to mimic a bonded monolithic restoration. The ceramic discs were etched, silanized and luted (Variolink N) into a dentin analogue material. Fatigue failure load was determined using the Staircase method (100,000 cycles at 20Hz; initial fatigue load ∼60% of the mean monotonic load-to-failure; step size ∼5% of the initial fatigue load). A stainless-steel piston (ϕ=40mm) applied the load into the center of the specimens submerged in water. Fractographic analysis and Finite Element Analysis (FEA) were also performed. ResultsThe ceramic thickness influenced the fatigue failure load for both ZLS materials: Suprinity (716N up to 1119N); Celtra (404N up to 1126N). FEA showed that decreasing ceramic thickness led to higher stress concentration on the cementing interface. SignificanceDifferent ZLS glass-ceramic thicknesses influenced the fatigue failure load of the bonded system (i.e. the thicker the glass ceramic is, the higher the fatigue failure load will be). Different microstructures of the ZLS glass-ceramics might affect the fatigue behavior. FEA showed that the thicker the glass ceramic is, the lower the stress concentration at the tensile surface will be.

Effect of Cr2AlC MAX phase addition on strengthening of Ni-Mo-Al alloy coating on piston ring: Tribological and twist-fatigue life assessment

The aim of the present study is to investigate the effect of Cr2AlC additions on the tribological properties of Piston Ring coated with Ni-Mo-Al alloy. For this Cr2AlC MAX phase was blended with Ni-Mo-Al alloy powder in different proportions (10wt%, 20wt% and 50wt%) and coated on the stainless steel piston ring by Air Plasma Spraying (APS). During coating Cr2AlC MAX reacts with air and forms Cr7C3 and Al2O3 phases. The in-situ formation of Cr7C3 and Al2O3 was observed to strengthen the alloy. 20wt% Cr2AlC additions to the Ni-Mo-Al alloy yields a good combination of properties, such as improved adhesion, hardness and wear resistance. Composite coating was found to be stable during the exfoliation test of the coated ring. Coating life cycles were found to be nearly doubled by MAX phase addition, as assessed through the twist-fatigue study. These improved properties could be attributed to the finely distributed oxides (alumina) and chromium carbides (Cr7C3) within the coated layer, which were formed in-situ during plasma spraying.

Microstructure characteristics of segregation zone in 17-4PH stainless steel piston rod

The segregation of Cu and Ni in a 17-4PH stainless steel piston rod has been confirmed to be responsible for the cracking after heat treatment. Further investigation showed that the segregation zone was composed of three layers, namely the fine grain martensitic layer, the coarse grain martensitic layer and the coarse grain austenitic layer from the matrix to the crack surface. Three button ingots with the same chemical compositions as those three layers have been prepared to evaluate the grain size distribution, microstructure and mechanical properties. The effects of Cu and Ni segregation on the microstructures of those three layers have been explored by thermodynamic calculation. Based on the microstructure and mechanical properties results, an intensive understanding of the cracking in the segregation zone was therefore reached.

Development and evaluation of low friction TiSiCN nanocomposite coatings for piston ring applications

Abstract To minimize the frictional losses and wear of piston rings in an automotive engine, thick low friction TiSiCN nanocomposite coatings have been developed. The coatings were deposited by sputtering titanium targets in argon, nitrogen, hexamethyldisilazane (HMDSN), and acetylene (C 2 H 2 ) using plasma enhanced magnetron sputtering (PEMS). The substrates were AISI 304 stainless steel coupons and piston rings with bore diameters of 137 mm and 86 mm. The elemental composition and microstructure of the coatings were optimized by varying the HMDSN and C 2 H 2 flow rates separately to achieve a combination of excellent adhesion, good mechanical properties, low coefficient of friction (COF) and wear rate. The optimized TiSiCN coatings exhibited a typical nanocomposite structure which showed excellent adhesion and dry COF in the range of 0.17 to 0.2 using a ball-on-disk tribometer. The tribological performance of the coated piston rings was evaluated using Plint TE77 tests in SAE 10W-30 diesel engine oil. The TE77 tests showed a 10% reduction in the COF (0.058) of the optimized coating compared to the uncoated baseline (0.065) at test conditions of 20 Hz, 30 N, and 25 mm stroke length. Finally, the coated rings were evaluated in a single cylinder gasoline engine using SAE 5W-20 engine oil and in a heavy duty diesel engine using 4.1% sooted SAE 10W-30 diesel engine oil. The gasoline engine test showed that the uncoated piston rings contributed 25% to 34% of the frictional loss in two separate baseline engine tests. In contrast, the coated rings contributed to 18% of the total frictional loss in the engine test. The diesel engine durability test showed a 28% and 40% lower ring weight loss for the coated top and second rings, respectively, as compared to the uncoated baseline. In addition, the cylinder liner, which was not coated, showed an average 50% lower wear than that in the uncoated baseline engine test.

Cracking due to Cu and Ni segregation in a 17-4 PH stainless steel piston rod

Abstract The 17-4 PH stainless steel is employed to produce piston rods in industry due to the high strength and toughness, good workability and nice corrosion resistance. In the present failure analysis, obvious long cracks were observed along the longitudinal direction on the surface of the commercial 17-4 PH stainless steel piston rod after heat treatment. The cracks were carefully looked into by observing the crack tip and characterizing the microstructure along the cracks. The results showed that the cracks were mostly initiated from the surface of the rod and propagated along the phase boundary between martensite and δ ferrite. The EDXA showed that the segregation of Cu and Ni should be responsible for the cracking after heat treatment. In order to define when the crack was coming into being, oxidation film along the crack was considered as a clue. The scrutiny of the oxidation film on the crack edge illustrated that the crack should be formed right in the heat treatment of aging.

Active Screen Plasma Nitriding

Abstract Active screen plasma nitriding and nitrocarburizing are relatively new processes in which a plasma discharge is applied to a metal screen surrounding the workload, generating highly reactive gas species that flow to the component surface. The active screen also radiates heat, resulting in a uniform temperature throughout the load. This article provides an overview of the two processes and presents examples of their use on stainless steel piston rings (nitriding) and 4142 and 1045 steels (nitrocarburizing).

Failure Analysis of Stress Corrosion Crack of 1Cr18Ni9 Stainless Steel Cylinder Body

As a kind of corrosion resistant material, stainless steel is widely used in petroleum, chemical, pharmaceutical. Stress corrosion cracking is a main reason that why the stainless steel became disabled. Therefore, it is very necessary to research and study the stress corrosion cracking of stainless steel .The failure analysis to the sample is conducted aiming at the stress corrosion of the stainless steel piston cylinder in a factory. The analysis includes macro analysis, metallographic observation, scanning electron microscopy analysis and XRD analysis. The results of the study show that it is nonmetallic inclusion on the grain boundary, the chloridion in the industrial circulating water and the rough columnar austenitic grains in the organization of the samples that lead to the stress corrosion cracking of the piston cylinder.

Hearing Results Using the SMart Piston Prosthesis

SMart, a newly introduced piston prosthesis for stapedotomy, is a nitinol-based, heat-activated, self-crimping prosthesis. We review our hearing results and postoperative complications using this self-crimped piston prosthesis and compare them with those obtained using stainless steel or platinum piston prostheses. Audiometric results using the SMart piston are identical to those obtained using a conventional piston prosthesis. Retrospective chart review. Private neurotologic tertiary referral center. The 416 ears reviewed included 306 with a SMart prosthesis and 110 conventional prostheses. 61% were women. Mean follow-up time was 5.6 (standard deviation [SD], 6.3 mo) and 6.9 months (SD, 7.0 mo) for the 2 groups, respectively. Stapedotomy using the SMart or a conventional (non-SMart) prosthesis. Audiometric hearing results, including pure-tone average (PTA) and air-bone gap (ABG), and prevalence of postoperative complications. Mean postoperative PTA was 32.6 (SD, 16.8) dB for the SMart group and 29.4 (SD, 13.5) dB for the non-SMart group, with ABGs of 7.6 (SD, 8.9) and 6.0 (SD, 5.2) dB, respectively. Mean change (decrease) in ABG was 18.7 (SD, 13.1) dB for the SMart group and 19.9 (SD, 10.3) dB for the non-SMart group. High-frequency bone PTAs showed overclosure of 2.0 (SD, 7.9) dB for the SMart group and 3.6 (SD, 8.6) dB for the non-SMart group. Postoperative vertigo and tinnitus were infrequent. No significant differences in these audiometric outcomes or complication rates were noted between groups. There was no significant difference in rate of gap closure to within 10 dB (78.3 versus 84.2%, SMart and non-SMart, respectively) or 20 dB (94.2 and 98.0%). Compared with conventional stapes prostheses, the nitinol-based SMart is a safe and reliable stapes prosthesis that eliminates manual crimping without significantly altering the audiometric outcome. Complications are rare, but longer follow-up is needed before establishing long-term stability.