Liner Surface Research Articles

Corrosion of a chimney liner operated for 130,000 hours

The tests were carried out for a coal-fired boiler heating a single-family house with a usable area of 220 m2. The tests covered the chimney liner (structure and surface layer - produced oxides/deposits), hard coal (eco-pea coal) and furnace ash. The chimney liner was located in a chimney made of bricks joined with concrete. A chimney liner made of austenitic steel was tested. The chimney liner was operated for 130,000 hours. The chimney insert was studied on the inner and outer side the respective cross-section. Coal with a grain size of 50-210 mm was analyzed. The bottom ash consisted of both loose ash and a mass of glassy sintered ash, the so-called slag. Thorough examinations of the researches materials comprised: microscopic examinations using an digital microscope VHX-7000 and scanning electron microscopes Jeol JSM-6610LV. Analysis of the chemical composition using Energy dispersive X-ray spectroscopy (EDS) in conjunction with the scanning electron microscopy (SEM). The surface topography (roughness) was measured using a VHX microscope using a Gaussian filter. The following parameters were determined on the basis of the tests: arithmetic mean height, maximum height, height of the highest peak, depth of the lowest depression, root mean square height, skewness, kurtosis.

Surface Texturing of Cylinder Liners: A Review.

The effect of cylinder liners on engine performance is substantial. Typically, the cylinder surfaces were plateau honed. However, recently additional dimples or grooves were created on them. This work discusses the tribological impacts of textured cylinder liner surfaces based on a review of the literature. The results of the experimental research obtained using test rigs and fired engines were critically reviewed. In addition, the results of the modeling are shown. Circular oil pockets and grooves perpendicular to the sliding direction of piston rings of small depths were typically used. Surface texturing of the cylinder liners governs lubrication between the cylinder liner and the piston ring by an increase in oil film thickness near the reversal points leading to reductions in friction force and wear and in the fired engine to a decrease in fuel consumption and to an increase in power or torque. The correct texturing pattern ensures a decrease in the oil consumption, blow-by, and emissions of the internal combustion engine compared to plateau-honed surfaces. Considerations of future challenges are also addressed. The volume of lubricant reservoir in surface topography, called oil capacity, should be a substantial parameter characterizing textured surfaces.

Effect Of Coatings On Softness And Surface Integrity Of Tissue Conditioners

Complete dentures loose its stability and retention due to the tomographic changes of the soft tissues and the residual alveolar ridges supporting the prosthesis. In such cases, tissue conditioners or resilient liners are the best treatment options to restore the health of oral mucosa and also to permit the use of denture and therefore there is a need to increase the longevity of these temporary liners and also provide surface smoothness to avoid irritation in the tissues. This can be achieved by the application of a layer of sealant over the surface of soft liners. Henceforth by evaluating the effects of two different surface coating materials viz Monopoly and Permaseal on the softness and the surface integrity of the two tissue conditioners, the tissue conditioners without a coat of sealants loses the quality of the softness in relation to time interval.

Synergetic effects of surface textures with modified copper nanoparticles lubricant additives on the tribological properties of cylinder liner-piston ring

The cylinder liner-piston ring (CLPR) is one of the most critical frictional pair for energy conversion in diesel engines. In this study, two forms of surface texture were respectively prepared on the liner surface by laser processing, with the modified copper nanoparticles (CNP) applied as the lubricant additives. The reciprocating tribometer and accompanying tribological testing technologies were then used to explore the synergetic effects of surface textures and additives on the tribological properties of CLPR. The results show that the composite lubrication system exhibits good friction-reduction and wear-resistance as the appropriate texture was adopted. Additionally, the synergetic effects among the storage capability of textures and the self-repairing ability of CNP additives can explain the improvement mechanism of CLPR’s tribological properties.

Design and Analysis of Cylinder Liner with Different Coatings

Abstract: In this project, the surface of a cylinder Liner in a diesel engine is coated with ceramiccoating powders by the plasmaspray technique using Ansys and its surface behavior is subsequently analyzed. The purpose of this study is to analyze with tribological effects of surface coating for a Liner in frictional mechanism. In, with and without coated cylinderliner was analyzed with Ansys software. The modeling and analysis of the cylinder liner is carrying by the catia and ansys software. Also, the combustion flow analysis of the cylinder liner is carried by Ansys software. From the obtained test results, it was found that the coated liner having improved properties in towards the diesel engine performance. The results show less deformation and fewer scratches due to wear on the Titania-coated Liner ascompared to uncoated one.

Effect of Laser Surface Texturing on the Tribological Properties and Scuffing Mechanism of CKS Piston Ring Against Cast Iron Cylinder Liner Under High Intensifying

The objective of this study is to characterize and understand the evolutionary processes that the effect of surface texture has on the tribology properties of the Chrom-Keramik-Schicht (CKS) piston ring/cast iron cylinder liner system under high intensifying. Surface dimple textures with an area density of 3–9% were prepared on the CKS piston ring by YAG laser, and the antifriction and antiscuffing properties were tested on a reciprocating test rig at 200 °C and 80 MPa. The minimum friction coefficient and wear loss were both obtained at the area density of 5%, compared with the untextured cylinder liner–piston ring (CLPR). The friction coefficient decreased by 0.013 to 0.086, and the wear loss for the piston ring and cylinder liner decreased by 41% and 46%, respectively. The sharp decrease of the friction force induced by surface polishing of the cylinder liner is taken as a sign to indicate the cylinder scuffing under starved lubrication. The scuffing time for the piston ring/cylinder liner system reached a maximum value of 18 min at an area density of 3%, which is extended about 41% compared with that of the untextured piston ring. The dimple surface texture on the piston ring could extend the scuffing time by delaying the occurrence of polishing behavior on the surface of cylinder liner. It is found that the retarded surface polishing played a major role for the modification of the antiscuffing property of the friction pairs according to the friction curves and wear morphologies.

Surface Roughness, Hardness and FTIR of the Modified Soft Liner with Different Metal Oxide Nanoparticles

Aims: To study the effect of metal oxide nanoparticles (MgO, ZrO2, ZnO) on acrylic based soft liner surface properties and FTIR. Materials and Methods: Acrylic-based soft-liner specimens were prepared by adding three different concentrations (0.5, 1, and 2) %wt of metal oxide nanoparticles (MgO, ZrO2, ZnO). A disk-shaped specimens with 30mm diameter and 3mm thickness were prepared for shore (A) hardness test to evaluate the surface hardness of modified soft liner. The surface roughness of soft-liner samples (10X10X2mm) was tested by a profilometer. FTIR analysis was conducted to evaluate chemical reaction that may occur between acrylic-based soft liner and nanoparticles. Results: there were no chemical reaction carried out between soft liner and metal oxide nanoparticles at different concentration- surface hardness (shore A) was increased as nanoparticles concentration increased in modified resin. Nanoparticles with 1 and 2% concentration incorporated in soft liner had lower surface roughness value. Conclusions: Metal oxide nanoparticles have improved the surface texture of acrylic-based soft liner, while the hardness of modified soft liner was increased with nanoparticles concentration increases.

Investigation of nuclear concrete

Recent times, life extension of nuclear power plant (NPP) plays one of the crucial roles in energetics and especially in nuclear industry. Key members of NPP's long term operation are reactor pressure vessel (RPV) and its cavity (concrete shell surrounding nuclear reactor). There is big interest in prediction of the state of biological shielding concrete around RPV. Many countries all over the world solve more or less the same problem: how to predict its state? Recent article provides with an opportunity of biological shielding concrete non-destructive testing (NDT). Two NDT methods will be performed as a possible solution of the problem. Due to high radiation, mechanical manipulators have been applied in order to attach ultrasonic or acoustic-emission transducers onto concrete surface or steel liner surface. The results will show 1) the possibility of the measurement near nuclear reactor in its outage, 2) the testing of RPV cavity from Greifswald's NPP NORD 3) and also the measurement of concrete samples irradiated by neutron and gamma radiation in light water reactor LVR-15. All presented material leads to the same goal: prolong the durability of old nuclear power plants and/or access their reliability and/or guarantee their safety.

On the influence of axial cylinder distortions on lubricant film and friction force of top piston ring conjunction near to TDC

ABSTRACT The purpose of this paper was to understand how axial cylinder distortions influence the tribological performance of piston ring. The current model contains the effects of axial distortions and ring conformability under mixed to hydrodynamic regimes of lubrication through computational fluid dynamics predictions. The axial cylinder profiles were modelled using series of sinusoidal waves. The effect of axial distortions on ring wear rate was determined using the Archard’s model. The ring friction and minimum lubricant film were predicted for low and high combustion pressures near to top dead centre. The study shows that, when the maximum combustion pressure rises, the different wear identities affect the operation of the ring friction much more limited, while the number of sine waves are more pronounced. Finally, it is proved that, even the increase of oil film thickness, it does not presuppose the reduction of friction when it comes to shaping the surface of the cylinder liner.

Evaluating the Performance of 3D-Printed PLA Reinforced with Date Pit Particles for Its Suitability as an Acetabular Liner in Artificial Hip Joints.

Off-the-shelf hip joints are considered essential parts in rehabilitation medicine that can help the disabled. However, the failure of the materials used in such joints can cause individual discomfort. In support of the various motor conditions of the influenced individuals, the aim of the current research is to develop a new composite that can be used as an acetabular liner inside the hip joint. Polylactic acid (PLA) can provide the advantage of design flexibility owing to its well-known applicability as a 3D printed material. However, using PLA as an acetabular liner is subject to limitations concerning mechanical properties. We developed a complete production process of a natural filler, i.e., date pits. Then, the PLA and date pit particles were extruded for homogenous mixing, producing a composite filament that can be used in 3D printing. Date pit particles with loading fractions of 0, 2, 4, 6, 8, and 10 wt.% are dispersed in the PLA. The thermal, physical, and mechanical properties of the PLA–date pit composites were estimated experimentally. The incorporation of date pit particles into PLA enhanced the compressive strength and stiffness but resulted in a reduction in the elongation and toughness. A finite element model (FEM) for hip joints was constructed, and the contact stresses on the surface of the acetabular liner were evaluated. The FEM results showed an enhancement in the composite load carrying capacity, in agreement with the experimental results.

Exploration on Nonaxisymmetric Flow Phenomenon in a Slinger Injector

The slinger is an important configuration of an aeroengine combustion chamber. It is well matched to smaller gas turbines that are more sensitive to cost than larger and more sophisticated models. The slinger combustor is inherently low cost itself, by eliminating fuel injectors and much of the fuel tubing and manifolding and also reducing costs in the requirements of the main fuel pump by operating at fuel delta pressures significantly lower than conventional fuel systems. The slinger's inherent drawbacks of increased combustion liner surface area and less atomization are less of a concern in a lower temperature, lower cost small turbines. The slinger's internal flow is of great significance to fuel atomization. This paper conducts experiments and numerical simulations on the slinger fuel injector. Numerical analysis and high-speed photography of the fuel slinger were applied to investigate the film flow pattern inside the slinger and the liquid phase distribution inside the combustion chamber to predict the flow field in an aeroengine combustion chamber. The transient Reynolds-averaged Navier–Stokes method, the volume of fluid method, and the discrete phase method were adopted in the simulation, and a high-speed camera and the rotational rig were used to perform the experiments. The nonaxisymmetric flow was present in the slinger and the combustor space. In the simulation results, the total mass-flow rate varies with time. Each hole's mass-flow rate value in the slinger is also different at the same time. The Sauter mean diameter (SMD) difference for each injection orifice is relatively small compared with the SMD difference caused by a rotation rate. The spatial distribution of the spray is also uneven as shown in the result of different single discharge channels' mass-flow rates. The experimental photos confirmed the simulation outcomes. The general theoretical analysis was made that these nonaxisymmetric phenomena were driven by the combined action of centrifugal force, surface tension, and instability phenomenon.

CAUSES OF DESTRUCTION DURING OIL STARVING IN THE FRICTION COUPLE "PISTON RING - CYLINDER LINER"

The study deals with the phenomenon of wear in the friction pair of the piston ring -cylinder liner during bench tests on prototypes. The tribological performance of dry frictionsimulating oil starvation was evaluated using the reciprocating motion of the tribometer. Significantwear was observed on the surface of the sleeve, made of gray cast iron, in contact with the chromesteel surface. This can be explained by a significant gradient in the rigidity of the tribopair inconjugation. With a chrome coating that has a noticeable hardness, extrusion and foaming of thesurface are observed along the edge of the sleeve, which indicates a change in wear. The coefficientof friction in dry sliding with stepped load increases showed an unstable state of friction, which isnot appreciated in the operation of any tribological system.Piston rings are used to seal the exhaust outlet gap between the piston and the liner for efficientoperation of the internal combustion engine. The distribution surface of the cylinder liner and pistonring during reciprocating motion is subject to continuous wear due to constant stresses, hightemperatures and intense loads. Thus, the performance and reliability of such heavy-duty enginecomponents depend on the topography of the conjugate surfaces and the associated tribologicalinteractions. Therefore, it is necessary to study the tribological behavior of conjugates of liners -rings that are subject to wear during oil starvation, and designed to effectively prevent exfoliation.This phenomenon leads to new surface coatings and modifications with significant wear propertiesin difficult operating conditions. Under certain conditions of loading, sliding and lubrication, the temperature rises to a criticalstate, the formation of the lubricating film is stopped and any formed lubricating film is destroyed,which leads to a catastrophic increase in friction. This continuous thermal feedback with the contactzone leads to wear of the friction pair of the piston ring - the cylinder liner. Given the changes in thedesign and materials of the engine, despite the fact that engine performance has increasedsignificantly with reduced emissions, it is impossible to exclude increased performance and enginefailure.

TRIBOLOGICAL PROPERTIES OF COMPOSITE PISTON RINGS DESIGNED FOR OIL-FREE CONTACTS IN ECOLOGICAL TRANSPORT

The paper presents a comparison of tribological properties for two generations of sliding contacts, i.e. TG15/ Anodic Hard Coating and PASL/AlMC in oil-free piston compressors designed for ecological transport. In the first contact, the piston ring material is Teflon-graphite TG15 (PTFE+15% graphite), and in the other, an acetal-based (PA) sliding composite (PASL) with additional substances acting as solid lubricants (SL), i.e. PTFE, graphite and carbon fibres. Rings made of plastics slide under conditions of technically dry friction against a cylinder liner’s surface made of aluminium alloy and reinforced by an electrolytic oxide coating (AHC) in the case of the first contact and with a cylinder liner surface made of alloy reinforced by the addition of Al2O3fibres (AlMC composite) in the latter contact. During friction, the wear debris of the filler form a sliding film (transfer film) on the cylinder liner’s surface, which results in a friction coefficient from 0.12 to 0.1 without the use of oil or greases.

Optimizing an acoustic liner by automatic differentiation of a compressible flow solver

The attenuation power of an acoustic liner is optimized by unsteady compressible flow simulations that model the presence of the liner with a time-domain impedance boundary condition (TDIBC). Two test cases are considered: a one-dimensional impedance tube and a two-dimensional grazing incidence tube. The impact of the liner on the pressure field is tuned through various TDIBC parameters imposed at the boundary where the liner surface is located. Automatic differentiation of the direct numerical simulation (DNS) code yields the gradients of the time-integrated pressure perturbations with respect to the TDIBC parameters. The gradients are subsequently used in an iterative process that minimizes the perturbations at a given location. In both test cases considered, TDIBC parameters are found which are more effective at attenuating perturbation frequencies other than those the initial TDIBC is designed to cancel. Finally, a sensitivity analysis reveals the importance of the choice of the initial TDIBC parameters for finding optimized settings. Our results pave the way to a wider application of the presented procedure in more complex problems with bulk flow motion and larger perturbation amplitudes.

CFD analysis of combustion liner with different geometry holes for effusion film cooling

The advanced gas turbine is designed to operate at higher temperature to increase thermal efficiency. Since the gas temperature exceed the allowable material temperature, so cooling techniques of turbine components are more important. Effusion film cooling is an external and highly sophisticated cooling technology, which protects the liner by injecting the secondary cooler fluid at particular locations over the liner surface exposed to the higher gas temperatures. The injected fluid forms as a thin layer (film) on the liner surface and protects the liner surface from higher gas temperatures. In elliptical geometry of holes in plate for effusion cooling is studied for the samples made of adiabatic and conductivity material. To increase the life of combustion chamber it is essential to know the amount of cooling air to be used for cooling of the liner. For effusion film cooling, geometry of the hole is one of the key parameters which influences the coolant mass flow rate and it spread over the liner surface thus affecting the cooling effectiveness. The commercially available FloEFD software is used for calculating the surface temperature and effusion cooling effectiveness distribution throughout the sample plate and result values are in good agreement and this has given confidence to usage of the commercial software FloEFD for predicting the film effectiveness. After result validation finally concluded that span wise elliptical hole (Config-2) have more effectiveness than circular holes.

Flow factor modeling of combustion engine ring and cylinder components in mixed hydrodynamic lubrication

This work employees the modification of the Reynolds equation for computational efficiency by analyzing rough surfaces in the hydrodynamic flow regime through the use of flow factors. This analysis is aimed towards modeling the surface interactions and pressure variations across power cylinder components of an internal combustion engine, namely the piston ring and cylinder wall. The Patir and Cheng equations are for general surfaces that accounts for the overall effect of roughness and anisotropic structure. However, rough surfaces are not fully characterized by these two parameters and therefore the aim of this paper was to provide flow-factors specific to the cross-hatched cylinder liner surfaces and piston ring interface. These interacting surfaces were measured directly through the use of a profilometer. Average flow factors are derived via full deterministic solution of the Reynolds equation over rough surfaces to model the pressure and shear variations relative to smooth surfaces. These flow factors can then be used to consider the effect of roughness in lubrication problems without deterministically modeling roughness.

Pressure on liner surface of the shaped charge with isosceles trapezoidal cross section

ABSTRACT An analytical model for calculating the pressure of detonation product on the liner surface was presented. Calculation results show that when the liner structure is the same, increasing the inscribed circle diameter of the charge cross section can reduce the influence of the charge nonaxisymmetry, when it is greater than the critical value, that is, 1.66× liner diameter, the pressure on liner surface is distributed axisymmetrically. Therefore, the jet of the shaped charge with isosceles trapezoidal cross section can be prevented from having an offset velocity by the above-mentioned method. This finding is verified through numerical simulation.

Low friction tribofilm formation and distribution on an engine cylinder tested with MoDTC-containing low viscosity engine lubricants

The piston-liner tribological contact has a key role in controlling friction caused energy losses in a passenger car engine. This study analyses the MoDTC-containing low viscosity lubricant performance and the resulting low-friction MoS2 tribofilm distribution on the liner surface. The engine liners were tested in a floating liner measurement system, where fully-formulated lubricants with different MoDTC concentrations were utilised to assess the impact of friction modifiers on the friction performance. Tested engine liners were dismantled from the measurement system, and MoS2 tribofilm formation on the liner was quantitatively characterised by Raman Microscopy mapping. The MoS2 tribofilm chemical composition and lamellar structure were further investigated by Transmission Electron Microscopy (TEM), High-Angle Annular Dark-Field Scanning (HAADF) and Energy Dispersive X-ray (STEM-EDX) Microscopy. The findings presented in this paper confirm that MoS2 tribofilm spatial distribution plays a pivotal role in reducing friction in piston-liner contact. 60% friction torque reduction was achieved at BDC area with 0.7% MoDTC concentration in the fully formulated lubricant. Moreover, MoS2 presence in the middle of the liner indicates MoDTC effectiveness throughout the whole engine cycle. Therefore, contributing to the overall energy savings in passenger cars.

CFD Analysis of the Effect of Dimples and Cylinder Liner Honing Groove on the Tribological Characteristics of a Low Displacement Engine

The contact between the piston rings and the cylinder liner is an interface with a strong influence on the tribological behavior and, therefore, directly affects the useful life of the engine components and fuel consumption. Due to this importance, the present investigation carried out an analysis of the effects of dimples and the honing groove in the cylinder liner on the tribological characteristics. A tribological model was developed to study the friction forces, minimum film thickness, and friction coefficient for the present investigation. Similarly, a computational fluid dynamics model was built to determine the dynamic movement of the piston. The validation of the numerical model showed a close similarity with the real behavior of the engine, obtaining an average relative error of 14%. The analysis of the results showed that a 3% increase in dimples’ density leads to a 3.79% increase in the minimum lubricant film and a 2.76% decrease in friction force. Additionally, it was shown that doubling the radius and depth of the dimple produces an increase of 3.86% and 1.91% in the thickness of the lubrication film. The most suitable distribution of the dimples on the surface of the cylinder liner corresponds to a square array. In general, the application of dimples and honing grooves in the cylinder liner are promising alternatives to reduce energy losses and minimize wear of engine components.

Ga-free AlInN films growth by close-coupled showerhead metalorganic chemical vapor deposition

In this paper, we have demonstrated that Ga-free AlInN can be obtained in the close-coupled showerhead (CCS) reactor metalorganic chemical vapor deposition (MOCVD) system when thorough cleaning was applied. For the AlInN films grown in the CCS reactor routinely used, the serious unintentional incorporation of gallium (Ga) atoms in AlInN was confirmed by the measurement results of secondary ion mass spectroscopy. To avoid the Ga incorporation, we removed the Ga-contained coatings on the surface of quartz liner, wafer susceptor, and showerhead. Then, in the reactor without Ga-contained coatings, Ga-free AlInN films were obtained. Moreover, the effect of growth parameters on the indium incorporation in AlInN and the structural properties of AlInN were studied systematically. It is worth noting that the realization of Ga-free AlInN in the CCS reactor is significantly important because CCS MOCVD system is widely used for the research and mass production of nitride materials and devices.