Cast Iron Piston Research Articles

Biolubricants and triboreactive materials for automotive applications

The research institution TEKNIKER has coordinated the EUROPEAN Project EREBIO, were different biodegradable lubricants have been formulated by FUCHS and BAM for heavy duty engines (GUASCOR), and passenger cars (RENAULT). In the frame of this article, it has been summarised the results obtained when developing biodegradable passenger car lubricants in combination with triboreactive materials. Replacing hydrocarbon-based oils with biodegradable products is one of the ways to reduce adverse effects on the ecosystem caused by the use of lubricants. The application of low or no sulphur, ash and phosphorous (lowSAP) ester- or polyglycol-based oils, intended for passenger car engine lubricants as substitutes for hydrocarbon-based oils, required the preparation of a composition of lubricants with comparable tribological and functional properties. The study is focussed on passenger car motor oils (PCMO) with reduced metal-organic additives. This is necessary in order to reduce the ash build-up in the after treatment system and therefore improve its efficiency and lifetime. High fuel efficiency and long drain intervals are requested, as well. To follow a line in a consequent way, these oils have to be biodegradable and non-toxic to the aqueous environment according to the directive EC/1999/45, coherent with other international standard. In a modern diesel or gasoline engine, the engine oils has to fulfil quite a number of different functions, such as lubricating and cooling the system, wear protection, soot and particle handling with less deposit tendency and so on. In the paper a study of the biodegradability, toxicity and the tribological properties has been carried out for new developed prototype engine bio-oils. Also, some different plasma sprayed triboreactive coatings have been deposited on cast iron piston rings, being studied also their tribological properties. Finally, the behaviour of the new bio-oils selected and plasma sprayed triboreactive coatings on piston rings have been screened in a real engine.

Influence of the coatings deposited by electrophysical methods on the wear resistance of the ends of piston rings

The reliability and durability of the piston–cylinder groups (PCG) of internal-combustion engines strongly depend on the dimensions of the clearance in the “piston ring–piston groove” joint whose limiting state leads to the fracture of the ring and failure of the engine. The increase in the clearance can, in fact, be regarded as the superposition of molecular, abrasive, and corrosion wear. The maximum wear is observed at the lower ends of the ring and the groove. For pistons made of cast iron, the degrees of wear of the ring and the groove are almost identical. At the same time, for aluminum pistons, the degree of wear of the joint is almost three times higher than for cast iron and the degree of wear of the harder end surface of the ring made of cast iron constitutes 70% of the total wear [1, 2]. In view of the world trend of boosting the engines, this problem becomes especially urgent and explains the extensive search of new methods aimed at increasing the wear resistance of the end surfaces of the rings [3, 4]. Since the deposition of electroplated chromium coatings (used on the working surface of the upper compression rings) on the end surfaces would lead to a severalfold increase in the laboriousness of their production, it is reasonable to study the electrophysical methods of surface hardening. The aim of the present work is to analyze the influence of the electric-spark alloying (ESA) and cathodic ion bombardment (CIB) of the end surfaces of cast-iron piston rings on their wear resistance under the conditions of molecular and abrasive wear.

Repairing the piston-cylinder group in a gas motorized compressor

A technology has been developed for repairing the worn cast-iron cylinder and piston in a motorized gas compressor: if the surface wear is more than 1.5 mm, sleeving is used, while with wear not more than 1.5 mm, gas-thermal coating is employed. Tests have been performed on a proposed material for plasma coating. There is a considerable increase in the working life of the repaired cylinders.

Wear response of crystalline nanocomposite and glassy Al2O3-SiC coatings subjected to simulated piston ring/cylinder wall tests

The present paper describes the major part of a recent research investigation whose main purpose was to develop a series of novel functional coatings based on the Al2O3-SiC system that ideally would have a nanocomposite microstructure. Such coatings should be well suited for the wear protection of steel and cast-iron piston rings used in automotive internal combustion engines. Two methods were investigated: (i) plasma spraying and (ii) magnetron sputtering. The former was applied to cast-iron and plain carbon steel, whereas the latter was applied to stainless steel piston rings. The plasma sprayed coatings were porous with a hardness of 900-1150 HV, whereas the sputtered coatings were glassy and dense with a hardness of 701-788 HV. High-speed reciprocation wear tests, which simulate the piston ring/cylinder wall environment, were used to assess all coatings. CKS-36 coated cast-iron rings, one of the more common industry standards for this application, were also evaluated. Results showed these to be the most wear resistant. They were smoothly worn, possibly by a microabrasion wear process. The plasma sprayed coatings displayed two main types of wear surface: rough and smooth. The former were mainly generated by a process of grain or particle pull-out, whereas the latter resulted from a combination of microabrasion and microflaking mechanisms. The use of diamond grinding, for finishing the plasma sprayed coatings, mitigated failure through grain pull-out, but wear rates still remained slightly too high compared with uncoated stainless steel and CKS-36 coated cast-iron rings. Most of the sputtered coatings displayed varying degrees of smooth wear which was mitigated as the coating hardness increased. However, this trend was masked by sporadic coating loss through adhesive and/or cohesive failure. The creation of a gradated sputter coating having a core composition based on the Al2O3-SiC variant containing most Si and C and incorporating a bond layer enriched in Cr, adjacent the substrate, eliminated cohesive and adhesive coating failures. Future work should concentrate on the development and evaluation of sputtered crystalline Al2O3-SiC coatings and HVOF sprayed Al2O3-SiC variants. There may also be significant potential in investigating glassy Al2O3-SiC coatings containing significantly higher quantities of Si and C to those reported here.

Influence of material properties on the wear of composite coatings

Aluminium matrix composite (AlMC) materials are finding more and more applications in machine construction. The addition of reinforcing materials to the matrix significantly improves the composite wear resistance. However, the presence of particles of a very hard, ceramic phase (Al 2O 3 and SiC) increases the wear of the sliding counterpart operating against the composite. Therefore, there exists a need to find methods of protecting the counterpart from the excessive wear. Cr+Al 2O 3 coating on cast iron piston rings running against the AlMC composite cylinders and anodic hard coating+metal (AHC+metal) type composite layer on engine cylinders elaborated at the Department of Material Science of the University of Silesia in Katowice are examples of such methods. In this paper, the mechanism of wear of the cast iron paired with AHC+Ni composite surface layer is presented. It is shown that wear depends on local material properties and stereological characteristics of the surface layer. The finite element method was used to determine the local stresses and strains.

Lubrication Properties of Inorganic-Organic Hybrids.

The development of fundamental processing technologies for low friction materials under boundary and fluid lubrication conditions, as well as technologies for incorporating flexibility into these materials for application to internal combustion engine components. The objectives of this study are as follows: (1) is to develop a piston ring with new inorganic-organic hybrid materials; (2) to reduce the friction to less than 80% of that in a cast iron piston ring. In this paper, the evaluation of friction and fundamental properties with test pieces was carried out. By changing the composition of inorganic-organic hybrid materials and control of heat treatment conditions, it is possible to eliminate cracking and to make the external surface flat and smooth. The possibility is confirmed of improving the friction property by controlling the wettability of inorganic-organic hybrids by oil addition.

Multi-layer compound coating on cast iron piston ring by multi-arc and magnetron sputtering ion compound plating technique

The Ti–TiN multi-layer compound coating on a cast iron piston ring utilizing the authors’ improved ‘multi-arc and magnetron sputtering ion compound plating device’ has been investigated by measuring the total thickness, fractography morphology, phases, micro-Vickers hardness, critical load, internal stress and wear resistance. The experimental results show that a Ti–TiN multi-layer compound coating thicker than 4 μm can be obtained on a cast iron piston ring, and the wear resistant properties of the cast iron piston ring-cylinder pair of an internal-combustion engine can be appreciably improved utilizing this technique.

Laser Hardening of Ring Grooves in Medium Speed Dieselengine Pistons

Internal combustion engine durability is enhanced if the side faces of the ring grooves in the pistons have a wear resistant surface. The present work concerns the development of a technique to achieve local hardening of medium speed steel crowned and cast iron pistons, based on the use of a 5 kW industrial laser. Specific aspects of the development which are discussed include: beam coupling and choice of absorbing coatings, choice of beam power density/interaction time, metallurgy, treatment of the edges of external corners, back tempering, and induced distortion and surface changes. The work has resulted in the treatment of prototype pistons for evaluation in engine trials.

Thermal and Thermoelastic Analysis of Spheroidal Graphite Cast Iron and Light Alloy Pistons

The results of theoretical thermal, thermoelastic, and mechanical analyses of a spheroidal graphite cast iron piston and an equivalent light alloy piston used hitherto are reported. The theoretical analysis was carried out using the finite elements method. Results obtained were experimentally verified by subjecting a spheroidal graphite cast iron piston to a peculiar load condition. The maximum stress values were found to be about the same in both pistons; so there is reason to believe that the spheroidal graphite cast iron piston can meet the same design requirements and even offer better performances than the light alloy piston.

Piston rings for slow and medium speed diesel engines: Aspects of manufacture and performance

The manufacture of piston rings for slow and medium speed diesel engines is a strange mixture of art and science whose final arbiter, the engine, is critical in its judgement of success or failure. Piston ring design is a delicate balance of tribology, practice, and manufacturing techniques, yet the piston ring is the least understood of all the components in a diesel engine, and the one most often found in practice to bear the brunt of the development problems of modern highly rated diesel engines. This paper presents a selection of some of the more practically orientated principles of the successful manufacture of grey cast iron piston rings greater than 175 mm in diameter, and shows that when considered with the sciences of strength of materials and diesel engineering, the subject of piston rings is almost an embodiment of the wider subject of tribology

Results of field tests on hardened cast iron piston rings

Results of field tests on hardened cast iron piston rings

Paper 2: Safety and Failure Analysis of Large Diesel Engine Pistons

This paper describes investigations that were undertaken to identify the reasons for fatigue failures in cast iron and aluminium pistons of large diesel engines. The work involved experimental and theoretical stress analyses, and fatigue tests were made on specimens cut from actual pistons. It was found that four pistons which suffered fatigue failures had safety factors of 0·60, 0·68, 0·94, and 0·96, while three modified designs which performed satisfactorily were assessed to have safety factors of 1·1, 1·24, and 1·57. Special attention is drawn to the method of fatigue testing in which features typical of the piston are retained. While it is considered prudent to design for safety factors substantially in excess of unity, the results presented should promote confidence that this approach to the design of components is valid not only in this case but more generally.

Structure of sulfocyanided layer on cast iron

1. The sulfide phases of the Fe−S system (FeS, Fe1−xS, Fe3S4, FeS2), were identified experimentally and by x-ray diffraction, and electron microscopic studies. These data were used for phase analysis of the diffusion layer on sulfocyanided cast iron piston rings. 2. Sulfocyaniding of cast iron piston rings leads to the formation of a diffusion layer of sulfides or nitrides. 3. Sulfocyaniding more than doubles the wear resistance of the rings.

Effects of Oil Jet Cooling on the Piston Temperature of Diesel Engine

In order to make clear the effect of the cooling methods and of the flow quantity of oil on the piston temperature, the authors have measured some temperature distributions over the cast iron piston of a small engine, with some thermocouples. As the result of a series of experiments, the following conclusions have been reached : 1) In case of the jet cooling, there is a critical oil flow beyond which even if we may increase the quantity of oil flow we can not expect the decrease of the piston temperature. It is 1.5∼2.0 l/cm2/h with respect to the surface area of the piston. (For higher speed, greater quantity required.) 2) At the critical flow, the mean coefficient of heat transfer from the inside of the piston crown to oil is 1600∼1700 kcal/m2h°C. 3) In utilizing the oil jet from the nozzle located at the small-end of the connecting-rod, the mean coefficient of heat transfer approaches to the maximum local coefficient.

On the Piston Temperature of the Old Type Japanese Farm Kerosene Engine

The temperature distribution of the cast iron piston under various running condition is measured with thermocouples. One of the authors (M. Hara) originates a new type hot junction of the thermocouple fixed directly at the thin wall of the piston body. From the experimental results, we come to the following conclusions : (1) The hottest part is locally situated in the centre of the piston head as being well known. (2) The temperature difference between the outer surface and the inner surface is very sma11 in the piston skirt. (3) The cooling water temperature has an important effect upon the piston temperature. (4) The more the fuel consumption, the lower the temperature of the piston head at full output. (5) The new type hot junction showed a satisfactory result.

Piston Temperatures in a Sleeve Valve Oil Engine

The paper describes tests on a Mirrlees-Ricardo sleeve valve engine of inches bore, running at speeds up to 1,400 r.p.m. The pistons used were: (1) a simple piston of cast iron; (2) a piston with tapered head section, cast in “L8” alloy; and (3) a heavily ribbed and strutted piston of “Y” alloy. A robust form of thermocouple gear which has been devised is described in the paper, and the probable errors are discussed. The temperatures attained by a number of points in each piston are shown for various conditions. The effect of the sleeve is much less than might be expected. The rates of heat reception by the central and outer portions of the piston head differ considerably owing to the vortex type of combustion chamber used. Values of these rates have been estimated for different loads and speeds. The alloy pistons become warm in about half the time required by the cast iron piston. Piston temperature appears to be a linear function of engine speed, the alloy pistons showing an increase of 42 deg. C. at the centre when the speed was increased from 800 to 1,400 r.p.m. at constant brake mean effective pressure. The temperatures of the lower edges of ribs of moderate depth were only 10–18 deg. C. cooler than the under surface of an unribbed piston. Distortion of the pin seatings due to the expansion of the struts must be very slight. With normal water circulation and a constant temperature of water supply, piston temperatures in this engine are almost independent of the final temperature of the water.

The Royal Research Ship Research

THE destruction of the non -magnetic ship A Carnegie by an explosion, at Apia, Western Samoa, on November 29, 1929, brought to a sudden end the magnetic survey of the oceanic areas, which had been carried on for twenty-five years by the Carnegie Institution of Washington. The Carnegie had been specially designed and constructed for obtaining magnetic observations at sea. She was a hermaphrodite brig, built of white oak and pine, with copper or bronze fastenings, and with a displacement of 568 tons. She was equipped with an auxiliary engine, capable of giving a speed of about 6 knots in calm weather; the engine was of internal combustion type and, at first, used gas generated from solid fuel, but, as this proved not altogether satisfactory, petrol was substituted. Sufficient fuel was carried to give a cruising range of 2,000 miles at 6 knots. With the exception of cast-iron pistons for the cylinders of the engine and the steel cams necessary for operating the valves, amounting in all to less than 600 lb., no magnetic material was used in the construction of the ship.

The Operating Temperatures of Cast Iron and Aluminium Pistons in a 12-Inch Bore Oil Engine

The engine used for these tests is of the single-cylinder vertical Diesel type, having a 12-inch bore and 18¼-inch stroke and running at 250 r.p.m. Temperatures have been measured at nineteen points on a ribbed “jam pot” cast iron piston, at twenty-three points on a “mushroom” type aluminium piston, and at fourteen points on a cast iron piston with a conical head support. Temperatures have also been measured at eight points on the cylinder liner. A description is given of the pistons and special testing apparatus. The influence of subsidiary junctions in the thermocouple leads, which led to some discussion following Dr. Mucklow's recent paper on piston temperatures,† has been studied. Errors, varying with engine output and amounting to as much as 29 deg. C., have been measured where no compensator was used. The effects of the temperature of the liner and of the jacket water outlet on the pistons have been measured, and are discussed. The conclusions are in general agreement with those of Dr. Mucklow except such as apply to the central portions of the heads, where the great differences of area exposed to flame lead to remarkably divergent results. The temperature distributions throughout the pistons are considered, and a quantitative estimate is made of the value of the neck, ribs, etc., when these are considered as heat channels. The radial temperature differences recorded for the aluminium and cast iron pistons and for the piston tested by Dr. Mucklow, are roughly in the ratio of 1/5½/19. The effect of varying the engine output has been studied, also the time required to warm up the pistons, the light alloy reaching its maximum temperature in approximately half the time required by the cast iron. A decrease in the number of rings from five to three is shown to have very little effect except in reducing the fuel consumption, while rings of forged “Y” metal slightly reduce the temperature of the piston. The effect of totally enclosing the piston shows that only some 2 per cent of the heat received is normally lost to the air circulating within it.