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Biodiesel is a biodegradable fuel that consists of alkyl esters, obtained from renewable sources, vegetal oil and animal fats reacting with a short-chain of aliphatic alcohols (typically methanol or ethanol) in the presence of a catalyst (reaction known as transesterification). An important property to use the biodiesel as fuel in diesel engines is its oxidation stability because biodiesel can contain unsaturated fatty acids, which are susceptible to oxidation, being able to change into polymerized compounds, which can cause engine problems such as blocked fuel filters. Numerous analytical methods have been applied to determine oxidation stability, European Union and Brazil use the same method DIN EN 14112 - known as Rancimat method that consists in the sample heating to 110°C where the products formed by the decomposition are blown inside by a flow of air in to measurement cell with distilled water.

Recently, a report was issued describing the use of an alternative to the commonly used thermocouple-probe assemblies for gathering time-temperature data to simulate microstructure, hardness and residual stresses of large castings of crack-sensitive steel alloys. This process involves the measurement of the increase of the water temperature in the quenching tank as a function of time as if the quench tank were a macro-calorimeter. From this data, cooling curves may be calculated which are then used to predict microstructure and hardness. However, no details of the actual modeling process used in that work have been published to date. This paper describes the results of a laboratory study which was recently performed using a round AISI 4140 steel bar to evaluate the feasibility of using water temperature rise during a quenching to generate a cooling curve for property prediction by simulation in a manner similar to that reported earlier.

The results of the stress relieving and tempering processes of steel are dependent on the process temperature and time which are correlated using Holloman-Jaffe equation or Larsen-Miller equation. These equations yield a value known as the tempering parameter, which is a measure of the thermal effect of the process. Processes that exhibit the same tempering parameter exhibit the same effect. In this paper an overview of the development of the tempering parameter, including its origin, use and limitations will be provided. In addition, recent work describing the development of more precise numerical relationships to describe the tempering process will be provided.

Although quench factor analysis has been used by many researchers in predicting the performance of a quenchant to strengthen aluminum, it has rarely been applied to steel quenching. However, quench factor analysis posses a number of advantages over current empirical methods or more recently employed finite element thermophysical property modeling. For example, quench factor analysis can address the non-Newtonian cooling process involved with many processes utilizing vaporizable quenchants. Quench factor analysis predictions of as-quenched hardness can be successfully performed with an Excel Spreadsheet calculation. Finally, quench factors can be easily utilized in constructing databases for quenchant characterization and selection.

This paper describes the use of computational simulation to examine the heat transfer properties and resulting residual stress obtained by quenching a standard probe into various quench oils. Cooling curves (time-temperature profiles) were obtained after immersing a preheated 12.5 mm dia. × 60 mm cylindrical Inconel 600 (Wolfson) probe with a Type K thermocouple inserted into the geometric center into a mineral oil quenchant. Different quenching conditions were used, as received (“fresh”) and after oxidation. Surface temperatures at the cooling metal - liquid quenchant interface and heat transfer coefficients are calculated using HT-Mod, a recently released computational code. Using this data, the temperature distribution was calculated. The corresponding residual stresses were calculated using ABAQUS. This work illustrates potential benefits of computational simulation to examine the expected impact of different quenchants and quenching conditions on a heat treatment process.

One of the most important heat treating processes is steel carburizing. However, the relatively long process times makes carburizing (and related thermochemical processes) a particularly energy consumptive and expensive process. Thus, if significant reductions in process times or temperatures can be achieved, this would result in substantial product cost savings and reduced energy consumption. Various methods of accelerating the carburizing process have been reported previously including: the use of rare earth metals, optimization by computer control of endo gas composition, use of superficial nitriding and others. In this paper, an overview of a new process using a hydrocarbon decomposition reaction catalyst that results in substantial diffusion rate acceleration and/or the potential use of significantly lower carburization temperatures will be discussed.

Surface engineering encompasses numerous vital and diverse technologies in the design and wear of automotive and off-highway components. These technologies include CVD, PVD, ion implantation and conventional heat treatments such as carburizing, nitriding and carbonitriding. Although these technologies are well known, it is considerably more difficult to understand the relative importance of the various technology niches for these processes, and it is very difficult to find effective summaries of the impact of these technologies on comparative lubrication formulation and practice. The objectives of this paper are two-fold. One is to review the impact of surface engineered coatings on the surface chemistry of steel. The second objective is to review the impact of the surface chemistry obtained by different surface treatments on boundary film formation to reduce frictional losses during fluid lubrication.

The effect phase composition of carburized constructional steels with a particular focus on the influence of retained austenite and carbides on hardness, impact strength and wear resistance is described. It is shown that increasing retained austenite and carbide content of the hardened carburized layers exhibits useful properties.

Atmosphere carburizing remains one of the most important surface treatment technologies throughout the world. In this paper, various important metallurgical design variables are identified by examining the results of the carburisation of 15HN steel. These results showed the importance of the formation of martensite-retained austenite-carbide microstructure after hardening. Increasing austenization temperature causes a decrease in the carbide fraction and an increase in the fraction of retained austenite. By optimisation of the composition of these microstructures through variation of carburisation process, hardening, and tempering variables, it is possible to optimise compressive stresses, abrasive wear resistance, and contact fatigue resistance.

Research results of structure and select properties (hardness, impact strength, wear resistance) carburized parts and tempered in three different cooling media: water, oil and aqueous polymer solutions are discussed. These results showed that structure and properties of case and core of carburized part is most profitable after using an aqueous polyalkylene glycol - PAG polymer solutions.

There has been an ongoing interest in replacing mineral oil with more biodegradable and/or fire-resistant hydraulic fluids in many mobile equipment applications. Although many alternative fluids may be more biodegradable, or fire-resistant, or both than mineral oil, they often suffer from other limitations such as poorer wear, oxidative stability, and yellow metal corrosion which inhibit their performance in high-pressure hydraulic systems, particularly high pressure piston pump applications. From the fluid supplier's viewpoint, the development of a definitive test, or series of tests, that provides sufficient information to determine how a given fluid would perform with various hydraulic components would be of interest because it would minimize extensive testing. This is often too slow or prohibitively expensive. Furthermore, from OEM's (original equipment manufacturer's) point of view, it would be advantageous to develop a more effective, industry accepted fluid analysis screening.

The ASTM test method D-2882 (Standard Test Method for Indicating the Wear Characteristics of Petroleum and Non-Petroleum Hydraulic Fluids in a Constant Volume Vane Pump) is widely used to evaluate hydraulic fluids. Performing this method can be difficult due to problems with the pump hardware and the written procedure. This paper discusses the problems and suggests possible remedies.

Cavitation is the dynamic process of gas cavity growth and collapse in a liquid. These cavities are due to the presence of dissolved gases or volatile liquids and they are formed at the point where the pressure is less than the saturation pressure of the gas (gaseous cavitation) or vapor pressure (vaporous cavitation). In this paper, various hydraulic system design factors and fluid properties affecting the cavitation process, and bubble collapse mechanisms will be discussed. In-situ generation of cavitation, examination of the cavitation process in model hydraulic systems, material effects and test methods will be reviewed.

There is increasing interest in the development of bench tests to characterize the performance of hydraulic fluids in order to minimize the cost of testing and the volumes of fluid currently required for pump testing. One method which permits comprehensive characterization of the boundary, mixed EHD and EHD wear regimes encountered in pump lubrication is to develop a performance map. This paper discusses the use of this testing method to characterize the performance of two experimental hydraulic fluid formulations.

One of the challenges in lubricant development is to adequately model performance across a broad range of potential lubrication and wear regimes that are encountered in use. Since wear in a given application is dependent on both rolling and sliding speeds, it is desirable to determine lubricant performance as a function of these variables. The use of a new test machine and methodology permits the construction of performance maps which define the transitions between lubrication regimes - hydrodynamic/elastohydrodynamic (EHD), EHD/mixed film and mixed film/boundary. This paper describes a method of mapping out the performance of a lubricant over a range of rolling and sliding velocities. Lubrication and wear performance is characterized for an ester base reference fluid (Herco-A) and two commercially available gear oils based on a petroleum oil and a poly(alpha olefin).