scispace - formally typeset
Search or ask a question

Showing papers in "International Journal of Powder Metallurgy in 1999"


Journal Article
TL;DR: In this article, the authors reviewed lesses in nanopowder densification and discussed which affer commercial potential for the commercial production of components with nanosize grains, and concluded that full consolidation of nanoparticles is a sensitive compromise between initial nanopowder characteristics, the several processing conditions in sintering such as pressure, temperature and time, and microstructural changes such as pore elimination and grain growth.
Abstract: The use nanocrystalline materials for novel applications requires the development of cost effective consolidation methods to generate engineering components. Full consolidation of nanoparticles is a sensitive compromise between initial nanopowder characteristics, the several processing conditions in sintering such as pressure, temperature and time, and microstructural changes such as pore elimination and grain growth. This paper reviews lesses in nanopowder densification and discusses which affer commercial potential for the commercial production of components with nanosize grains.

83 citations


Journal Article
TL;DR: In this paper, a new class of grain growth inhibitor alloys is developed, which gives better control of WC particle coarsening during liquid phase sintering of nanophase WC/Co powder compacts.
Abstract: A new class of grain growth inhibitor alloys has been developed, which gives better control of WC particle coarsening during liquid phase sintering of nanophase WC/Co powder compacts. The new alloys are formulated as solid solutions of the selected inhibitor carbide phases (VC and/or Cr 3 C 2 ) in the Co metal binder phase. The solid solution approach realizes a much more uniform dispersion of the inhibitor carbides in the nanocomposite material thereby ensuring more effective mitigation of WC grain growth during sintering. A significant reduction in the melting point of the Co-rich matrix by the addition of the inhibitor phases contributes to the reduced WC coarsening rate. Another contributing factor, and possibly a decisive one, is the formation of stable metal/non-metal clusters, e.g. W,V, Cr/C clusters, in the liquid Co. Such clusters are believed to impede liquid phase transport of W and C atoms from one grain to the next adjacent one, thus further restricting the WC coarsening rate.

36 citations


Journal Article
TL;DR: In this article, the authors link the processing parameters with the resulting density, microstructure, and thermal properties, and link these processing parameters to the resulting resulting density and micro-structure.
Abstract: Mo-Cu is desirable for thermal management applications because of its combination of low thermal expansion coefficient and high thermal conductivity. Depending on the degree of shape complexity required for specific applications, powders can be consolidated by either die compaction or powder injection molding. The starting powder may be elemental Mo, which is infiltrated with Cu after pre-sintering, or it may consist of a blend of Mo and Cu powders, which are liquid phase sintered to near full density. The processing route selection is based mainly on shape complexity, but requires specific attention to several processing parameters including particle size, green density, and the thermal cycle. This work links these processing parameters with the resulting density, microstructure, and thermal properties. Long sintering times and controlled cooling rates are needed for high density, high thermal conductivity heat sinks processed via liquid phase sintering. On the other hand, thermal conductivities of 160 W/mK are achieved for Mo-15Cu through infiltration of either injection molded or die compacted Mo skeletons. The higher green densities available from die compaction enable pre-sintering of the Mo skeleton with shorter, lower temperature thermal cycles . Furthermore, the pre-sintering and infiltration cycles can be combined into a single step. Thus, infiltration of die compacted specimens is preferred except for the most complex heat sink geometries. For these cases, infection molding is demonstrated as an alternate processing route.

24 citations


Journal Article
TL;DR: In this paper, a debinding cycle was identified which resulted in a high surface quality of the bionic parts, shape retention, and complete removal of binder, and an intermediate isostatic repressing step increased bionic density but did not contribute significantly to densification during sintering.
Abstract: Nanostructured W-Cu composite powder was fabricated by mechanical alloying. Compacts were then prepared from the powder in the as-milled conditions, and after a thermal reduction treatment, by metal injection molding using a multicomponent wax/polyethylene/stearic acid binder system. A debinding cycle was identified which resulted in a high surface quality of the bionic parts, shape retention, and complete removal of the binder. An intermediate isostatic repressing step increased the bionic density but did not contribute significantly to densification during sintering. Densities >96% of theorical were achieved in the injection molded compacts for both powder conditions via liquid phase sintering, notwithstanding the low brown density after debinding. This high sinterability is attributed to grain growth of the W and a double rearrangement process in the powder due to its intrinsic nanostructural characteristics.

19 citations


Journal Article
TL;DR: In this article, the authors present a commercial rolling contact fatigue test bench, which is suitable for testing porous materials, such as wrought, cast, and P/M materials, under variable loading conditions, allowing the life time calculation for a given load-time history.
Abstract: Details of a commercial rolling contact fatigue test bench are given; its design permits the evaluation of the rolling contact fatigue behavior of different materials, and makes it suitable for testing porous materials. Without additional machining the original as-sintered surface is tested. Elastohydrodynamic lubrication is applied, which is essential for testing porous material under realistic service conditions. Using the test bench, material behavior under variable loading conditions can be studied, allowing the life-time calculation for a given load-time history. Following a brief overview of rolling contact fatigue, results obtained with the test bench on wrought, cast, and P/M materials are given and analysed. The change from open to closed porosity in sintered steel influences significantly endurance limit and this impacts the development of new, high loading structural parts such as planetary gears and camshaft lobes.

19 citations


Journal Article
TL;DR: Metallic nanopowders can be produced by applying a high power electrical pulse to a wire while in argon as mentioned in this paper, where the electromagnetic field created by the pulse confines the plasma until the vapor pressure of the metal exceeds the ability of the field to cantain it and on explosion accurs, creating metallic clusters of spherical particles.
Abstract: Metallic nanopowders can be produced by applying a high power electrical pulse to a wire while in argon. The electromagnetic field created by the pulse confines the plasma until the vapor pressure of the metal exceeds the ability of the field to cantain it and on explosion accurs, creating metallic clusters of spherical particles. Rapid adicbatic quenching creates defects in the particles and they behave as if they are extensively warked, with a lowering of recrystallization temperature and the release of energy when the powders reach a threshold temperature substantially below melting. The powders are highly reactive and some are pyrophoric. Applications include their use in prapellants, explosives and pyrotechnics, as chemical reactants for organic synthesis, as catalysts, as conductors in microelectronics and as a sintering aid. Kilogram quantities of the following metals have been fabricated by this technique: nickel, iron, tungsten, tin, aluminum, copper, zinc, titanium, silver and indium.

18 citations


Journal Article
TL;DR: In this paper, the results of a study of an alternative net shape powder processing route, using vacuum degassing, compaction and sintering of a prealloyed 6061 Al powder.
Abstract: The present powder metallurgy production route for sintered aluminum alloy parts is based on the liquid phase sintering of premixed powder compacts. This paper presents the results of a study of an alternative net shape powder processing route, using vacuum degassing, compaction and sintering of a prealloyed 6061 Al powder. The compacting conditions were varied to determine their effects on the green density and green strength of the compacts prepared from the as-received and degassed powders. Using the same compacting conditions, the compacts prepared from the degassed powder were sintered at three different temperatures within the melting range of the alloy to determine the effect of this parameter on sintered density and tensile properties. The degassing was found to increase the green density, and the transverse rupture strength of green compacts was a factor of two greater for the degassed powder. Furthermore, the tensile properties of the degassed and sintered powder compacts were higher than those of equivalent alloys prepared for blended powders and comparable to the tensile properties achieved via degassing and hot extrusion of the prealloyed 6061 Al powder.

15 citations


Journal Article
TL;DR: In this article, the supersolidus liquid-phase sintering of compacts prepared from the degassed powder has been studied by dilatometry and metallography, and the results identify the effects of compaction and sintered conditions on green and Sintered properties such as density and dimensional change.
Abstract: Prealloyed 6061 Al alloy powder has been degassed and die compacted under different conditions of temperature and pressure. The supersolidus liquid-phase sintering of compacts prepared from the degassed powder has been studied by dilatometry and metallography. The results identify the effects of compaction and sintering conditions on green and sintered properties such as density and dimensional change. The present study attempts to isolate critical processing parameters in terms of oxide layer break-up and optimal sintering.

15 citations


Journal Article
TL;DR: In this paper, the simulation of powder injection molding of an M2 tool steel is computer simulated with respect to sintering densification, distortion, and microstructure coarsening.
Abstract: Tool steel powders are available with particle sizes in the range suitable for injection molding. In most regards the processing is similar to other forms of powder injection molding. However, sintering densitication without distortion proves difficult. In this study, the powder injection molding of an M2 tool steel is computer simulated with respect to sintering densification, distortion, and microstructure coarsening. The simulations are customized to M2 tool steels for powder injection molding. Some solid state sintering occurs during heating, but full density requires supersolidus liquid phase sintering. Once the solidus temperature is reached, liquid films spread on the grain boundaries, resalting in rapid grain growth. Consequently, the grain size often exceeds the initial particle size prior to full densification. These special characteristics are included in the simulation, allowing prediction of optimal sintering conditions. A time-temperature sintering window is computed for full density without extensive corbide coarsening or shape distortion. For an alloy containing 0.85w/oC, the recommended temperafure is just over 1255°C for times near 30min. The optimal sintering temperature decreases as the carbon content increases. The simulation compares favorably with distortion and densification findings from M2 tool steel compacts.

15 citations


Journal Article
TL;DR: Supersolidus liquid phase sintering was used to process powder injection molded low and high carbon grade M2 tool steel, formed with a polyacetal based binder and subjected to catalytic debinding as mentioned in this paper.
Abstract: Supersolidus liquid phase sintering was used to process powder injection molded low and high carbon grade M2 tool steel, formed with a polyacetal based binder and subjected to catalytic debinding. This is a technique whereby a prealloyed powder compact is heated above the solidus temperature to form internal liquid which densifies the compact rapidly. Full density processing was possible without significant distortion in thick sections. Carbon control was achieved through temperature and atmosphere control in debinding and sintering. Debinding and sintering cycles were generated, through dilatomatry, sintering experiments, carbon analysis, and metallography. After catalytic removal of the polyacetal binder, samples were debound in a 50v/o H 2 /5Ov/o N 2 atmosphere in a retort furnace heated at 5°C/min to 600°C for 1h, then heated at 10°C/min to 850°C for 30min. Samples were sintered in 15v/o H 2 /85v/o N 2 in a batch furnace heated at 10°C/min to the sintering temperature for 30min. The sintering temperature window which produced full density with well dispersed carbides was determined to be 1275 to 1287°C for 30min. A high carbon grade which (1w/o) was processed for comparison to the low carbon grade (0.83w/o) showed similar densification behavior, at approximately 25°C lower temperatures.

13 citations


Journal Article
TL;DR: The major challenge has been to maintain an vitrafine grain structure in the consolidated material, which is relatively easy to achieve in thermal spraying of coatings, because of the shart particle residence times in the hot zone of the plasma or combustion flame.
Abstract: During the past year, several cenferences have focused on the synthesis and processing of nanestructured materials, as well as their properties and performance in cansalidated forms. PM 2 TEC99 provided yet anather forum for scientific and technical discussions in this rapidly growing field. In what follows, we will present highlights of the progress being made in the nanomaterials field. One of the mast significant developments has been the shift in emphasis from powder synthesis to powder consolidation. The major challenge has been to maintain an vitrafine grain structure in the consolidated material. This is relatively easy to achieve in thermal spraying of coatings, because of the shart particle residence times in the hot zone of the plasma or combustion flame. On the other hand, consalidation of bulk materials, involving solid or liquid phase sintering, inevitably exposes the materials to high temperatures for much longer times so that grain coarsening is more difficult to circumvent.

Journal Article
TL;DR: In this article, another type of filler material comprising highly porous metal powders (nanopowders) is evaluated that leads to improved thermonechanical properties of the composites at reaonably high electrical conductivity levels and reduced metal contents.
Abstract: Polymer found materials are made electrically conductive by compounding with a particulate conductive material. Carbon seat is used most often in anti-static applications and electromagnetic shielding. In this paper another type of filler material comprising highly porous metal powders (nanopowders) is evaluated that leads to improved thermonechanical properties of the composites at reaonably high electrical conductivity levels and et reduced metal contents. Such powders are produced by the inert gas condensation technique. The broad range of applications is exemplified with a cycloaliphatic epoxy matrix for use in electronic packaging. The mechanical properties of the cured polymer, nanopowder composites have been tested under shear loading and -40°C/150°C thermal cycling conditions. It is shown that these highly porous powders counterbalance the embrittling effect of a metal filler in polymer matrix composites. The underlying concept is not limited to conductive adhesives for chip-on-board bonding in the microelectronics industry.

Journal Article
TL;DR: In this paper, the microstructures of the coatings and the powders were investigated using scanning electron microscopy and X-ray diffraction, and room temperature dry sliding wear tests were performed using the block-on-ring test.
Abstract: High Velocity Oxygen Fuel coatings were produced using powders with different chemical compositions, and the microstructure, hardness and sliding wear behavior studied with reference to the characteristics of the starting powders. The microstructures of the coatings and the powders were investigated using scanning electron microscopy and X-ray diffraction. Room temperature dry sliding wear tests were performed using the block-on-ring test. Wear behavior of the coatings is anderstood in relation to the applied load, sliding speed and wear surface damage.

Journal Article
TL;DR: In this paper, the effect of polyethylene lubricants on the compaction and ejection of aluminum alloy powder compacts fabricated from spherical powders has been assessed, and it was shown that polyethylenes have adequate lubricating properties and permits the compacting of aluminum powder without die-wall lubrication.
Abstract: Lubricants are generally admixed with metal powders to facilitate compaction and to minimize forces during ejection of the part from the die. In order to optimize the mechanical properties of alominum components fabricated by powder mettalurgy, the lubricant shoold not irapede the formation of interparticle contacts during compaction. Also, it should burn out cleanly at relatively low temperature, (420°C) to avaid reactions between aluminum and the lubricant or decomposition products. Here, the effect of admixing a polyethylene lubricant on the compaction and ejection of aluminum alloy powder compacts fabricated from spherical powders has been assessed. This polymer has adequate lubricating properties and permits the compaction of aluminum powder without die-wall lubrication. Components fabricated with polyethylene exhibit significantly higher green and sintered properties than components fabricated with a conventional amide wax lubricant.

Journal Article
TL;DR: In this article, the data recorded during the compression of a part in five kinematic conditions are presented, and results are analyzed in relation to the kinematics and forces acting during compression and during removal of the tools.
Abstract: Data recorded during the compression of a part in five kinematic conditions are presented. Parts were made on a press instrumented to measure the forces acting on the tools and their displacements. After ejection, local densities were measured, and observation of the outer surfaces revealed defects. Results are analyzed in relation to the kinematics and forces acting during compression and during removal of the tools. A data base is established which, when combined with the characteristics of the powder, allows for a comparison with actual cases for numerical simulation.

Journal Article
TL;DR: The driving force for sintering in the Fe-Cu-C system induced by the gap in carbon concentration between iron particles, and the driving force arising from differences in surface curvature, have been evaluated quantitatively as discussed by the authors.
Abstract: The driving force for sintering in the Fe-Cu-C system induced by the gap in carbon concentration between iron particles, and the driving force arising from differences in surface curvature, have been evaluated quantitatively. It is shown that the former is at least one order of magnitude larger than the surface curvature effect. Under the influence of the driving force of carbon, a semipermeable layer of liquid capper forms which prevents carbon diffusion, but which allows iron to be transported between particles, thereby enhancing sintering. This pehnomenon appears to control copper-growth of the ferrous compact. Neck formation in a columnar structure is shown to be an example of liquid boundary migration in which particle coalescence occurs.

Journal Article
TL;DR: The North American P/M industry has enjoyed seven years of steady growth with metal powder shipments reaching 511,185st (464,053mt) in 2016 as mentioned in this paper.
Abstract: The North American P/M industry has enjoyed seven years of steady growth with metal powder shipments reaching 511,185st (464,053mt). Growth markets include iron and steel, stainless steel, alaminum, copper and tool steel powders. The auto market continues to dominate the conventional P/M parts industry. Hot isostatic pressing, metal injection molding and powder forging are also growing. The need for global P/M materials standards is becoming increasingly important.

Journal Article
TL;DR: The first serious R&D activities involving hot isostatic pressing in the former USSR began in the 1960s and focused on rotating parts made from Ti and Ni-base powder alloys to be used in jet and rocket engines.
Abstract: The first serious R&D activities involving hot isostatic pressing in the former USSR began in the 1960s and focused on rotating parts made from Ti and Ni-base powder alloys to be used in jet and rocket engines. The technology and production processes developed employed hot isostatic pressing as a final consolidation and shaping operation for near net shapes. In the decade from 1980 to 1990, more than 40,000 turbine and compressor disks and other rotating parts were hot isostatically pressed for different types of engines. Following the collapse of the USSR, however, the level of these programs was reduced significantly. New initiatives from industry resulting from east-west economic and technical cooperation revived interest in near net shape and net shape hot isostatic pressing technologies in Russia. This article examines emerging cooperation with US companies in the production of complex shape critical parts and components utilizing hot isostatic pressing. Major scientific and technical tools developed, results, progress and participants are reviewed.

Journal Article
TL;DR: In this article, a method of recording the molten metal height with time using a conducting metal height detector was presented, which was used in a model to characterize the friction losses in the metal delivery system.
Abstract: One of the most important process variables in gas atomization is the gas to metal mass ratio (GM) as it has a direct effect on the mean particle size of the atomized powder. If this ratio can be controlled during the atomization process the powder produced would be more uniform and the d50 more predictable. Thus, atomization using a fundish or gravity feed from a crucible would be more stable. In gas atomization, the gas flowrate can be monitored easily but it is very difficult to determine the molten metal flowrate. This paper presents a new method of recording the molten metal height with time using a conducting metal height detector. The metal height recorded in real time during atomization was used in a model to characterize the friction losses in the metal delivery system. It is found that the integrity of the metal delivery tube and the cleanliness of the melt each plays a key role in maintaining a stable metal feed.

Journal Article
TL;DR: In this paper, a commercial finite element program was used for the calculations with boundary conditions and assumptions based on experimental results, and the temperature history of the billet was calculated during and after spraying.
Abstract: During the production of large diameter spray formed copper and alloy steel billets, hot cracks were observed at the head with residual melt present during crack initiation. Temperature simulations were carried out to investigate the hot cracking phenomenon in the spray forming process. A commercial finite element program was used for the calculations with boundary conditions and assumptions based on experimental results. The temperature history of the billet was calculated during and after spraying. It is shown that different spray parameters influence the radial thermal gradient, especially at the top of the billet; reduced heat input at the top of the billet decreases the thermal gradient. In the experiments hot cracks are reduced or avoided with a lower heat input.

Journal Article
TL;DR: In this article, spray cast composites of Al-Si/SiC p were fabricated by atomizing the alloy melt with a mixture of nitrogen gas and SiC p partides.
Abstract: Spray cast composites of Al-Si/SiC p were fabricated by atomizing the alloy melt with a mixture of nitrogen gas and SiC p partides. Microstructure was monitored in the spray cast condition, after hot extrusion, and in the over spray powder. Dry sliding wear response was assessed for the extruded composite, extruded unreinforced Al-Si, and extrudad mold cast Al-Si. SiC p particles are embedded in the droplets and result in a homogeneous dispersion of reinforcement. Presolified droplets containing SiC p and the composite preforms exhibit a uniform distribution of the eutectic silicon phase, and a finer equiaxed grain size than the reinforced spray cast aluminium alloy. For the unreinforced preform, eutectic silicon crystalllizes at the triple points of the aluminium grains with a blocky morphology. For droplets reinforced with SiC p the particles act as nucleation sites for eutectic silicon during solidification and the eutectic silicon retards grain growth during spray casting. The distribution of SiC p particles in the preform is affected by the fraction of liquid phase on the upper surface of the preform and by its solidification rate. Microstructural observations on the spray-cast and hot extruded composites reveal that the average size of the grains and the Si phase become finer, and the aspect ratio of the Si phase decreases, with an increase in v/o SiC p . The morphology of the Si phase changes from rod-like to blocky and globular with an increase in v/o SiC p . Sproy-cast and hot extruded composites show improved wear resistance compared to the mold-cast and hot extruded alloy. This is attributed to the presence of a fine grain size and the fine Si phase with a blocky morphology. Increasing the v/o SiC p improves the wear resistance of the composites.

Journal Article
TL;DR: In this paper, a plasma sprayed aluminum-based composite (Al-SiC) was found to be more suitable than current metallic or ceramic coatings for the use in automobile blocks and other critical parts.
Abstract: The use in automobile blocks and other critical parts such as cam rods and valves requires superior surface properties. This has led to the development of thermally sprayed surface coatings for this type of component. To impert maximum band strength and superior wear resistance, a plasma sprayed aluminum based composite (Al-SiC) was found to be more suitable than current metallic or ceramic coatings. To eliminate inhomogeneities arising from blended powders, composite powders were prepared by mechanical alloying of 6061 Al alloy with SiC particles. The concentration of SiC was varied between 20 and 75v/o. The size of the reinforcement was varied from 8 to 37μm in the Al-50v/o SiC composites. An organic process control agent was used to modify the morphology of the powders during mechanical alloying. The 44 to 140μm powders were sprayed using an axial feed plasma forch. Adhesion strength, hardness, abrasive and erosive wear resistance of the coatings were assessed.

Journal Article
TL;DR: In this article, a vapor phase synthesis process was developed in which vapors of chemical precursars were pyrolyzed in a low pressure flat flame, and high surface area nanopowders of oxides that have primary and secondary (aggregate) nanosscale particle sizes.
Abstract: Nanophase powdears («100nm diameter) offer a host of attractive properties that are different from these associated with coarser particles. With the growing number of applications for this new class of powders, several techniques have evolved ever the past several years for the synthesis of metal and ceramic powders. At issue in each of these processes is the extent of agglomeration (particle adhesion) and aggregation (particle sintering). While it is virtually impossible to eliminate agglomeration of pristine nanopowders due to strong van der Waals forces of attraction that keep the particles together, aggregation depends on the technique used for producing nanoparticles. We have developed a vapor phase synthesis process in which vapors of chemical precursars are pyrolyzed in a low pressure flat flame. By controlling the time-temperature history of the particles in the hot zone of the flame, we have produced high surface area nanopowders of oxides that have primary and secondary (aggregate) nanosscale particle sizes. The synthesis process, scalability issues, powder properties and areas of application are described.

Journal Article
TL;DR: For example, hot isostatic pressing is the preferred commercial process for achieving full density in parts made from metal powders as mentioned in this paper, where gas-atomized, pre-alloyed powders are normally used.
Abstract: Over the last 25 years, thousands of powder metallurgy parts have been consolidated to full density by hot isostatic pressing and used in many critical applications. With an annual production approximating 6.8M kg (7,500st), hot isostatic pressing is the preferred commercial process for achieving full density in parts made from metal powders. To ensure uniformity and process consistency, gas-atomized, pre-alloyed powders are normally used. These powders are essentially spherical and are processed through the steps of screening, blending, and container loading prior to hot isostatic pressing. Following consolidation, parts may be used as is, or they may be thermo-mechanically processed, heat treated, and/or non-destructively tested, depending on final usage. Applications taking advantage of the improved performance of hot isostatic pressed powder metallurgy parts include high temperature rotating components for aircraft and marine gas turbine systems, corrosion resistant pressure bearing components for petrochemical equipment, nuclear reactors, medical implants and components for hot and cold working tools and dies.

Journal Article
TL;DR: In this article, a heuristic model was proposed to predict porosity of spray forming of tool steels using the effect of relative magnitudes of the fluid flow characteristic time and the solidification characteristic time on the porosity formation process.
Abstract: The objective of the present study is to provide a numerical model to serve as a guide in the determination of optimum processing parameters for the spray forming of tool steels. Porosity is predicted using a heuristic model that incorporates the effect of the relative magnitudes of the fluid flow characteristic time and the solidification characteristic time on the porosity formation process, Two regimes, the 'fast flow' regime and the 'fast salidification regime, are identified a priori. Expressions for porosity as a function of the particle size distribution, the over-age solid fraction of the incident spray, and the solidification contraction are derived, based on these assumptions. The average solid fraction of the incident spray is estimated from the droplet size distribution and the solid fraction of a single droplet of a given size. The fatter is determined by cakulating the droplet dynamics and thermal history. The effects of process parameters (melt superheat, atomization pressure, deposition distance, and melt mass flow rate) on the level of porosity are investigated. By determining the conditions corresponding to a minimom in predicted porosity, optimum processing parameters can be assessed. As a result, processing maps are provided as a reference for achieving spray fermed tool steels with minimum parosity.

Journal Article
TL;DR: In this article, the authors examined the application of deterministic chaos theory and fractal geometry to characterize the effects of lubricants on powder flowabitity, including zinc stearate, polyvinyl fluoride, Teflon (polytetrafluoroethylene -PTFE), and Acrawax C (ethylene bis-stearamide), with irregularly shaped iron powders.
Abstract: The use of lubricants in die compaction is becoming an increasingly important issue in the P/M industry, both from an economic and environmental perspective. To date, the evaluation of lubricants, has been limited primarily to apparent density, tap density, and various elementary flow tests. This study examines the application of deterministic chaos theory and fractal geometry to characterize the effects of lubricants on powder flowabitity. The lubricants that were investigated included zinc stearate, polyvinyl fluoride, Teflon (polytetrafluoroethylene -PTFE), and Acrawax C (ethylene bis-stearamide), admixed with irregularly shaped iron powders. In addition to distinguishing between the efficacy of various lubricants, data are presented on statistical reproducibility, the effect of testing history on measurements, and the effect of machine operating parameters on the data. Parameters are discussed that can be used to describe lubricant flow date produced by this new technique.