Vacuum Process Research Articles

Experimental Study on Microstructural Changes of Nanoaluminum Particles during the Slow Heating Process in Vacuum and Aerobic Environments

Experimental Study on Microstructural Changes of Nanoaluminum Particles during the Slow Heating Process in Vacuum and Aerobic Environments

Fracture behavior, mechanical properties, and microstructural analysis of vacuum automated GMAW welded dissimilar A353 and A516 steels for pressure vessels

In this study, the performance of the automatic gas metal arc welding (GMAW) process in vacuum for similar and dissimilar joints of A353 and A516 steel plates with different thicknesses was intensively evaluated. Fracture of all vacuum-welded samples occurred in the heat-affected zone (HAZ) of A516 steel, highlighting the significant influence of HAZ microstructure and width on the cryogenic impact energy and strength of these joints. According to microscopic observations and impact tests, the fractures were fully ductile for notches in the weld and A353 HAZ, where dimples were observed on the fracture surfaces and the impact energy exceeded 50 J. This ductile behavior is particularly significant for notches in the weld due to the presence of a vacuum during welding prevents the formation of gas voids and oxide and hydride compounds that are normally the origin of cracks. However, for notches in the A516 HAZ, where the cleavage faces were observed on the fracture surfaces and the impact energy was less than 30 J, the fractures were quite brittle. For dissimilar vacuum-welded samples, the impact energy and fracture type for notches in the weld and A353 HAZ were nearly the same as those in similar A353 joints. However, for notches in the A516 HAZ, the impact energy and fracture type were close to those observed in the A516 joints. Yield strength and ultimate tensile strength (UTS) of A353-A353 non-vacuum-welded samples compared to vacuum-welded samples decreased by more than 78% and 40%, respectively. As well as, yield strengths and UTSs of A516-A516 non-vacuum samples compared to vacuum samples decreased by more than 34% and 4%, respectively. On the other side, the impact samples with a notch position in the weld suffered brittle fracture instead of ductile fracture because their impact energy decreased by about 40%.

Quantitative Modelling of Residual Molecular Contamination in Low-Pressure Processing Environments

Some published experimental results of organic molecule contamination in vacuum processing are reviewed. The build-up of gaseous contamination from the residual gas in vacuum ambient to the surface of a substrate is quantitatively modelled. Calculations show that the build up of contaminants from the residual gas phase to the surface is very fast, essentially because in very dilute gas there are little molecular collisions to slow down the transport towards the substrate.

A Facile Low Prevacuum Treatment to Enhance the Durability of Nonfullerene Organic Solar Cells

Herein, a straightforward vacuum‐assisted method is introduced to enhance the stability of nonfullerene organic solar cells (OSCs). The method, termed “prevacuum” involves subjecting the active layer (D18:Y6) to a low‐pressure vacuum (−1 bar) before thermal annealing at 100 °C. Compared to untreated devices, prevacuum‐treated OSCs exhibit a notable increase in power conversion efficiency from 13.71% to 14.90%. This enhancement is attributed to improved light absorption and charge extraction, as evidenced by external quantum efficiency measurements. Moreover, prevacuum treatment significantly improves device stability under operational conditions, with a 30% power loss occurring after 8.25 h compared to 4.5 h for untreated devices. This improvement is attributed to the removal of volatile components and impurities during the vacuum process, leading to a more hydrophobic and stable active layer. The study demonstrates the efficacy of prevacuum treatment as a simple and accessible method for enhancing the performance and longevity of OSCs, paving the way for their broader application in sustainable energy technologies.

Highly efficient and thermally stable photonic ceramic by controllable and full crystallization from glass

Polycrystalline ceramics are promising for a diverse range of applications in solid state laser, lighting, scintillator and optical storage. Unfortunately, current ceramic elaborations involves strict and complex synthetic procedures such as ultra-high pressure and vacuum processing. Here, we realize the tune of MgAl2Si4O12 and Mg2Al4Si5O18 phase formation in a glass by controlling the two crystal nucleation and growth individually, and obtain a polycrystalline non-stoichiometric Mg2-x/2Al4-xSi5+xO18:Eu2+ translucent ceramic by virtue of complete and congruent crystallization of the glass. Microstructural characterizations verify that the resulting ceramic exhibits dense and closely stacked micrometer-scale crystallites with very thin grain boundary structure. Chemical composition analysis by energy dispersive X-ray spectrometry revels the grain's composition is highly deviated from the stoichiometric Mg2Al4Si5O18, with atomic ratio Mg/Al/Si of 1.00: 1.46: 2.70. The precipitated non-stoichiometric Mg2-x/2Al4-xSi5+xO18, structurally having infinite channels z = 0.25 or 0.75 sites that run parallel to the c-aix, provides an robust crystal-field environment for Eu2+ 5d-4f transition. As a consequence, the ceramic produces intense emission with photoluminescence quantum yield (PLQY) up to 90 %, and excellent thermal stability emission with 70.1 % emission intensity at 420 K relative to that at room temperature, demonstrating it can be applied in high power lighting application with improved light quality by employing the ceramic as a color converter. Moreover, the ceramic also exhibits thermally stimulated luminescence at temperature reaching up to 700 K, originating from the deep electronic traps in Mg2-x/2Al4-xSi5+xO18 lattice with estimated trap depth of 0.73eV and 0.97eV. We also demonstrate the ceramic is hopeful for optical information storage application as the storage information can be retain well without vulnerable by the fluctuations of external environments due to the deep traps.

ANALYSIS OF MODERN TECHNICAL SOLUTIONS FOR VACUUM COATING FORMATION TECHNOLOGIES USED IN THE AVIATION FIELD

Modern requirements for technologies and mechanical engineering products necessitate the creation of new technological methods for processing materials and the development of appropriate technical means. Promising are environmentally friendly vacuum, ion, beam and photonic processes for obtaining materials, applying various coatings, and creating multilayer structures. An urgent scientific and technical problem is the creation of devices and methods for processing materials, vacuum devices for producing composite materials and forming coatings. It is known that significant parameters of materials are determined by the properties of their surface layers, therefore surface treatment technology, including the application of coatings and the creation of complex structures based on them, is of great importance. Vacuum-thermal and plasma surface treatment processes are promising in this regard.

Ripple formation on TA2 pure titanium surface induced by annular laser beam at low pressure environment

Formation of the micron-scale circular ripples on metal surfaces produced by continuous wave laser irradiation in low-pressure environment was investigated experimentally and numerically in this manuscript. It is found that splashing of the molten material and oxidation of the metal surface, which usually happened in the atmospheric environment, were avoided in low-pressure environment. Therefore, circular ripples were formed during the solidification process of the molten pool. Numerical simulations based on the finite element method (FEM) and the moving mesh method were applied to investigate the evolution of the flow field behavior of the molten pool. It is found that the Marangoni effect and capillary force during solidification process dominate the formation of the micron-scale circular ripples. In addition, the ripple spacing can be controlled by the temperature gradient. At the same power density, a higher temperature gradient on the molten surface can be produced by an annular laser beam, compared to a Gaussian beam, thus a denser circular ripple structure were produced, which were confirmed by the experimental results. The results of this paper may enrich the investigations on the metal surface texturing methods, laser vacuum processing and laser material engineering.

Development of an ultra-clean sample heating stage for thermal desorption spectroscopy

Control of surface molecular contamination (SMC) for components used in chemical vapor deposition (CVD), atomic layer deposition (ALD) and EUV photolithography is important to maintaining high yield and optimal tool operation at the latest process nodes in leading edge semiconductor manufacturing. High temperature thermal desorption spectroscopy (TDS) is a versatile tool for analyzing the cleanliness of surfaces, simulating thermal vacuum processes and studying the kinetics of desorption processes. A basic analysis of TD spectra allows for full characterization of volatile outgassing from surfaces, while detailed analysis can provide chemical information about the substrate surface.In fundamental studies, TDS is often carried out from low temperatures to room temperature or for small samples. However, for microelectronics applications, high temperature studies of large (100 mm or greater) samples are of greater interest due to direct applications for cleanliness testing and thermal vacuum simulation. A limitation for TDS sensitivity is the outgassing of sample stage materials, particularly when analyzing gases that may be present in the chamber background such as water, CO and CO2. Typical sample stages are often tested only for total pressure or at room temperature.In this study, we present a simple ultra-high vacuum (UHV) compatible sample heating stage for trace outgassing analysis of 100 mm samples at high temperatures. Simulation results are presented to support the feasibility of the concept. Experimental results verify the cleanliness of the stage via room temperature residual gas analysis (RGA) analysis and X-ray photoelectron spectroscopy (XPS) of stage components. Finally, use of this stage in a TDS analysis of a 100 mm Si witness wafer and comparison to room temperature RGA demonstrates operational capability.The sample heating stage is both shown to be clean at high temperature and capable of analyzing 100 mm wafers to higher sensitivity than room temperature RGA for all m/z at the 1 × 10−9 mbar level. Despite its high performance, the heating stage is also easily produced by any laser machining service, greatly improving the accessibility of UHV science for all researchers.

Effect of solution‐processed cesium carbonate on Cu(In,Ga)Se2 thin‐film solar cells

AbstractHeavy alkali‐metal treatments have been the most recent breakthrough in improving the efficiency of Cu(In,Ga)Se2 (CIGS) solar cells. Alkali halides are generally evaporated onto the surface of the CIGS thin film by a vacuum process. Here, we report an alternative, low‐cost solution process for the surface treatment of CIGS thin films using cesium carbonate (CsCO3) as a new route to incorporate cesium (Cs) for improving solar cell performance. CIGS thin films were fabricated using pulsed hybrid reactive magnetron sputtering and the surface treatment was performed by spin‐coating CsCO3 solution on the surface of CIGS at room temperature, followed by vacuum annealing at 400°C. The surface chemistry of the CIGS thin film changed after the treatment and the efficiency of respective solar cells improved by more than 30%, mostly driven by an enhancement in open‐circuit voltage. X‐ray photoelectron spectroscopy revealed the depletion of copper and the presence of Cs on the surface of the CIGS thin film. Ultraviolet photoelectron spectroscopy showed the lowering of the valence band maximum by around 0.25 eV after the treatment, which plays a positive role in reducing interfacial recombination. High‐resolution transmission electron microscopy indicates the presence of Cs and depletion of Cu at the grain boundaries of the CIGS thin film. These findings open a low‐cost route for improving the performance of CIGS solar cells by surface modification using a solution process.

Flexible Graphene-Based Sensors for Electrochemical Analysis of Human Saliva and Sweat

Flexible carbon nanomaterial sensors offer a low-cost, facile fabrication approach toward producing sensors at an industrial scale for electrochemical sensing. Graphene and carbon nanotube (CNT) based sensors have been studied, with various fabrication methods available, including producing high-quality thin film graphene and CNTs via chemical vapor deposition (CVD). However, CVD is a high-temperature vacuum process that is low-yielding and consequently costly, hindering its implementation into single-use test strip sensors. Other methods, such as inkjet or aerosol printing, are more cost-effective as they print graphene inks obtained from liquid-phase exfoliation of graphite, which can be performed using large batch processing techniques. Additionally, the laser-induced graphene (LIG) technique directly converts sp3 carbon found in carbon-rich substrates, such as polyimide, into conductive sp2-hybridized carbon found in graphene through a laser scribing technique. Saliva and sweat offer promising biological fluids for precision health monitoring and diagnostics due to the non-invasive nature of their sampling (no need for a blood draw at a laboratory or a fingerstick at home) and due to the abundance of medically relevant analytes. Saliva can also be used for monitoring infections such as COVID-19 infection. Herein, we introduce graphene-based flexible sensors fabricated using scalable manufacturing based on aerosol jet printing (AJP) using custom-formulated graphene inks and laser-induced graphene via direct writing. We report a label-free, high-sensitivity, and rapid-response-time graphene-based electrochemical immunosensor for quantitatively detecting the SARS-CoV-2 Spike Receptor-Binding Domain (RBD) as well as SARS-CoV-2 Spike S1 protein. We demonstrate LIG-based electrochemical sensors for real-time monitoring of glucose, lactate, and sodium in sweat, and potassium and lactate in saliva. Different electrochemical methods are used, including amperometric, potentiometric, coulometric, and impedimetric, to quantify the analytes. All these electrochemical sensors were validated in human saliva and sweat and demonstrated to have limits of detection and linear sensing ranges that are relevant to their sensing applications. Flexibility studies were also performed to evaluate the ability of the sensors to operate under stresses caused by bending, such as those that would be encountered by skin and implanted oral sensors. Results demonstrate the utility of AJP-graphene and LIG for rapid and sensitive measurement of biological analytes and pathogen infection as simple methods for scalable production of non-invasive salivary and perspiration (sweat) health sensors.

In situ monitoring of industrial-scale chemical vapor deposition using residual gas analysis

The maintenance of industrial-scale equipment demands more effort and incurs higher costs compared to that of laboratory-scale equipment, necessitating the use of predictive maintenance techniques to mitigate unforeseen outcomes. This paper presents a demonstration of the in situ monitoring of industrial-scale low-pressure chemical vapor deposition equipment by using a residual gas analyzer (RGA). The RGA provides reactions of precursor gases by tracing the concentration and composition of residual gases within vacuum reactors. Furthermore, RGA analysis enables the prediction of the growth rate of the thin-film, providing insights into thin-film growth dynamics during the process. In situ monitoring using an RGA can be applied to diverse semiconductor fabrication processes, including thin-film growth, oxidation, reactive ion etching, and ion implantation, owing to its compatibility with vacuum processes. This study addresses the existing difficulties in the exploration of RGA monitoring techniques for industrial-scale equipment and bridges the disparity between laboratory-scale and industrial-scale processes.

Enhancing Photocathodic Performances of Particulate-CuGaS2-Based Photoelectrodes via Conjugation with Conductive Organic Polymers for Efficient Solar-Driven Hydrogen Production and CO2 Reduction.

Modification with conductive organic polymers consisting of a thiophane- or pyrrole-based backbone improved the cathodic photocurrent of a particulate-CuGaS2-based photoelectrode under simulated solar light. Among these polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) was the most effective in the improvements, providing a photocurrent 670 times as high as that of the bare photocathode. An incident-photon-to-current efficiency (IPCE) for water reduction to form H2 under monochromatic light irradiation (450 nm at 0 V vs RHE) was ca. 11%. The most important point is that modification of the conductive organic polymers does not involve any vacuum processes. This importance lies in the use of an electrochemically oxidative polymerization, not in a physical process such as vapor deposition of metal conductors. This is expected to be advantageous in the large-scale application of photocathodes consisting of particulate photocatalyst materials toward industrial solar-hydrogen production using photoelectrochemical-cell-based devices. Artificial photosynthesis of water splitting and CO2 reduction under simulated solar light was demonstrated by combining the PEDOT-modified CuGaS2 photocathode with a CoOx-loaded BiVO4 photoanode. Furthermore, how the cathodic photocurrent of the particulate-CuGaS2-based photocathode was drastically improved by the modification was clarified based on various characterizations and control experiments as follows: (1) selectively filling cavities between the particulate CuGaS2 photocatalysts and a conductive substrate (FTO; fluorine-doped tin oxide) with the polymers and (2) using a large driving force for carrier transportation governed by the polymers' redox potentials adjusted by functional groups.

Vacuum processing temperature effect on highly coercive recycled NdFeB permanent magnets with Pr-based alloy addition

This study presents a modified method for recycling NdFeB scrap magnets, producing up to 100 kg of recycled sintered NdFeB magnets per batch. By adding a Pr-based alloy to N40H-grade NdFeB scrap and optimizing vacuum sintering and heat treatment conditions, we enhanced the magnetic properties and corrosion resistance of the recycled magnets. Various analyses, including BH Tracer measurements, FE-EPMA, accelerated corrosion tests, and C/N/O content analysis, evaluated differences in magnetic properties, microstructure, corrosion resistance, and impurity content. Optimal recycling involved vacuum sintering at 1085 °C, followed by heat treatments at 900 °C and 470 °C. Recycled magnets with PrCoGa alloy showed superior properties, such as an intrinsic coercivity (iHc) of 1414 kA/m, remanence (Br) of 1.290 T, and a maximum magnetic energy product ((BH)max) of 315.4 kJ/m, meeting N40H standards. Accelerated corrosion tests also indicated enhanced corrosion resistance in recycled magnets with Pr90Co8Ga2 alloy. This research offers a commercially viable approach for NdFeB magnet and rare earth element recycling.

Analysis of Maintenance Methods and Process Improvement of Vacuum Laser Collimation System for Dams

The method and process of vacuum laser collimation system maintenance is one of the key technologies directly related to the accuracy of dam vacuum laser collimation system measurement value. Taking the maintenance methods and processes of vacuum laser collimation system in Lianlu and Xiacheng as the background, a new set of dam vacuum laser collimation system maintenance methods and processes are proposed, aiming to make up for the gaps in the maintenance of vacuum laser collimation system. It was found that the vacuum pipeline operates at vacuum values between 400 Pa and 900 Pa. The influence of light on the vacuum laser is avoided by correcting the system and shading the transmitting end as well as the connecting part of the receiving end and the vacuum pipeline with a rubber sheet. This new maintenance method and process also provides a useful reference for the safety monitoring of similar projects.

Laser-induced graphene van der Waals contact-enabled high-performance 2D-materials-based field-effect transistor

Establishing robust electrical contact between electrodes and two-dimensional (2D) semiconductors has become an increasingly critical challenge in realizing high-performance 2D material-based devices. This study presents an easy-to-fabricate high-quality van der Waals (vdW) contact strategy, utilizing transferred laser-induced graphene (LIG), for monolayer graphene field-effect transistors (LIG-GFETs). LIG-graphene vdW contacts were formed via a simple transfer and alignment step without any high-temperature or vacuum processes. Excellent electrical properties of LIG-GFETs were achieved, with up to sevenfold enhanced carrier mobilities compared to conventional gold electrode-based GFETs. Experimental investigations and density functional theory simulations elucidated the mechanisms underlying this performance enhancement. Specifically, the superior performance of LIG-GFETs can be attributed to the formation of vdW contacts between the transferred LIG and the monolayer graphene, alongside the doping of the monolayer graphene induced by the O functional groups in the LIG. We also demonstrated that the high performance monolayer MoS2 FETs can be achieved with more than fivefold enhanced carrier mobilities by using LIG vdW contact compared to conventional gold electrode-based MoS2 FETs. This newly developed vdW contact strategy provides new insights into high-performance 2D material-based devices.

Purification of Used Lubricating Oils Using Vacuum Distillation

Engine oil (EO) is produced by mixing base oil derivatives from crude oil with chemical additives to the lubricity of moving parts and reduce the friction inside the engine. Used lubricating oil (ULO) is one of the hazardous materials that consists of pollution harmful to the environment, it needs to be managed properly. In this work, vacuum distillation technique is used to recycle used lubricating oil. Used lubricating oil samples from two different brands of diesel engine oil (20w-50) and gasoline engine oil (10W-30) are used in this study. Various properties of ULO and recycled oil were characterized such as kinematic viscosity, viscosity index, density, pour point, flash point, Sulphur content, and Fourier transform Infrared spectroscopy FTIR. The yield recycles for ULO of gasoline engines, diesel engines, and mix (gasoline and diesel) by vacuum process were 85%, 74%, and 75% respectively, it was discovered that the sulfur component decreased from 9792.3 ppm of ULO to 405 ppm of yield distillates. The pour point results show an increase from -30 °C of used lubricating oil to -18 and -6 for distillates cut for vacuum distillation, compared to the pour point of Iraqi base oil 40 and 60 Stook (SN150 and SN200) -18 °C and -6 °C

Post-annealing in ultra-high vacuum or nitrogen plasma for MoS2 thin films deposited by magnetron sputtering

The thin films of amorphous molybdenum disulfide were deposited at room temperature by magnetron sputtering technique. Post-annealing process in ultra-high vacuum (∼10−8 Pa) or nitrogen plasma environments at the temperatures of 300, 400, 500, and 700 °C have been first proposed to enhance the microstructure and optical properties of MoS2 thin films. The phase transformation of MoS2 thin films from amorphous to polycrystalline was characterized by in situ reflection high-energy electron diffraction during the post-annealing process. The microstructure of MoS2 thin films was also analyzed by Raman spectrum and X-ray diffractometer after the post-annealing process. In addition, the thermal analysis of the differential scanning calorimeter and optical measurement of photoreflectance confirmed the phase transformation of MoS2 thin films. The analysis of photoreflectance also estimated the exciton transition at the bandgap energy of 2.038 eV at 0 K, attributed by the crystalline MoS2 film annealed at 700 °C in ultra-high vacuum. The surface chemical composition of MoS2 thin films has been identified by X-ray photoelectron spectroscopy, but the desulfurization of MoS2 was observed after post-annealing in ultra-high vacuum. Moreover, the preferred orientation of (004) plane in the MoS2 films was performed as the increase in post-annealing temperature.

Operational experience with Adaptive Gain Integrating Pixel Detectors at European XFEL

The European X-ray Free Electron Laser (European XFEL) is a cutting-edge user facility that generates per second up to 27,000 ultra-short, spatially coherent X-ray pulses within an energy range of 0.26 to more than 20 keV. Specialized instrumentation, including various 2D X-ray detectors capable of handling the unique time structure of the beam, is required. The one-megapixel AGIPD (AGIPD1M) detectors, developed for the European XFEL by the AGIPD Consortium, are the primary detectors used for user experiments at the SPB/SFX and MID instruments. The first AGIPD1M detector was installed at SPB/SFX when the facility began operation in 2017, and the second one was installed at MID in November 2018. The AGIPD detector systems require a dedicated infrastructure, well-defined safety systems, and high-level control procedures to ensure stable and safe operation. As of now, the AGIPD1M detectors installed at the SPB/SFX and MID experimental end stations are fully integrated into the European XFEL environment, including mechanical integration, vacuum, power, control, data acquisition, and data processing systems. Specific high-level procedures allow facilitated detector control, and dedicated interlock systems based on Programmable Logic Controllers ensure detector safety in case of power, vacuum, or cooling failure. The first 6 years of operation have clearly demonstrated that the AGIPD1M detectors provide high-quality scientific results. The collected data, along with additional dedicated studies, have also enabled the identification and quantification of issues related to detector performance, ensuring stable operation. Characterization and calibration of detectors are among the most critical and challenging aspects of operation due to their complex nature. A methodology has been developed to enable detector characterization and data correction, both in near real-time (online) and offline mode. The calibration process optimizes detector performance and ensures the highest quality of experimental results. Overall, the experience gained from integrating and operating the AGIPD detectors at the European XFEL, along with the developed methodology for detector characterization and calibration, provides valuable insights for the development of next-generation detectors for Free Electron Laser X-ray sources.

Comparative Analysis of Industrial and Homemade Strawberry Jam Processing: Quality, Degradation, and Energy Consumption

Purpose: Compare certain steps of strawberry jam processing, energy consumption, waste generation, as well as indicators of jam quality obtained through industrial and homemade methods. Method/design/approach: The jams were prepared in the fruit and vegetable laboratory as well as in the pilot plant. The bottling process involved hot sealing in glass jars with metal lids. After sealing, the jars were inverted, cooled, and stored at -18 °C until analysis. The ingredients used included high methoxyl pectin, citric acid, sucrose, and fresh acidic lemon juice. The analysis included the use of various chemicals such as methanol, sodium acetate, potassium chloride, hydrochloric acid, NaOH, ascorbic acid, dihydrated oxalic acid, and 2,6-dichloroindophenol. Results and conclusion: The study examined industrial, semi-industrial, and homemade jams, highlighting changes in color parameters and losses of anthocyanins and ascorbic acid over time. Homemade jams exhibited greater variations in both color and processing. Strawberry pre-processing and water consumption differed between industrial and homemade productions, with a higher disposal rate observed in industrial production. The yield of industrial jams remained consistently above 90%, whereas homemade jams showed variations. Energy consumption was higher in homemade jams, making the industrial process more energy-efficient. Industrial vacuum processing provided advantages such as lower temperatures, reduced sensible heat, and minimized chemical changes, but it necessitated more expensive and maintenance-intensive equipment. Originality/value: In contemporary discourse, there has been substantial censure directed towards industrialized foods in recent years, with a considerable portion lacking a rigorous scientific foundation. This study contributes by presenting findings that facilitate the discernment of advantages stemming from both industrial and artisanal processes, contingent upon the availability of requisite technical knowledge.

The effect of vacuum process on biodiesel production from Palm Kernel Fatty Acid Distillate

This study examines the operating pressure effect on the manufacture of biodiesel from Palm Kernel Fatty Acid Distillate (PKFAD) by using para-Toluene Sulfonic Acid (PTSA) catalyst. The operating pressures studied are the vacuum pressures of 70 kPa, 80 kPa, 90 kPa, and 100 kPa, which varied with PTSA concentrations of 5%, 10%, 15%, 20%, and 25%, and the molar ratios of methanol and PKFAD are 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1. Biodiesel production from PKFAD was carried out with reaction duration of 120 minutes and reaction temperature at 50 0C. The amounts of fatty acids converted to biodiesel were calculated based on the initial and acid numbers after the esterification reaction. The results show that a vacuum pressure of 70 kPa to 100 kPa provides a conversion above 96% for all catalyst concentrations and all methanol and PKFAD molar ratios. The highest conversion of PKFAD to biodiesel of 98.6% is obtained at an operating pressure of 80 kPa, a catalyst concentration of 25%, and the molar ratio of methanol and PKFAD is 10:1. The biodiesel characteristics obtained in this study have met the standards of the American Society for Testing Materials.