Deposition Rate Research Articles

Morphology of films deposited on the sidewall during the Bosch process using C4F8 plasmas

Abstract In the Bosch process, C4F8 plasmas are used to deposit passivation films. In this study, the passivation films were deposited in micro-scale trenches by changing the C4F8 flow rate, ICP power, and pressure, and their cross sections were observed by scanning electron microscopy. The results showed that the morphology of the passivation film and its relative deposition rate at each depth varied depending on the plasma discharge conditions. There is a correlation between the C–CFx bond content and the morphology of passivation films, with high C–CFx bond content resulting in smooth morphology and low C–CFx bond content resulting in a rough morphology. Furthermore, it was found that ion bombardment reduced the roughness of the passivation film. Through these experiments, we also found the possibility of controlling the deposition rate of the passivation film at each trench depth by adjusting the plasma discharge conditions.

Nano-silica modified with silane and fluorinated chemicals to prepare a superhydrophobic coating for enhancing self-cleaning performance

ABSTRACT Superhydrophobic coatings with excellent self-cleaning performance have attracted significant concerns from researchers. Although various superhydrophobic coatings with prominent superhydrophobic properties have been fabricated, most developed coatings are still inadequate in pipeline scale inhibition applications. In this work, nano-silica (nano-SiO2) was modified by silane coupling of vinyltriethoxysilane (VETS) and 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFTS) to prepare a superhydrophobic coating. Organosilicon of PFTS and VETS was grafted onto the surface of SiO2 for preparing the superhydrophobic coating with low surface energy, and the superhydrophobic coating was cured via poly(vinylidene fluoride) (PVDF). The results showed that the contact angle of the prepared silica-based superhydrophobic coating, denoted as VETS-PFTS@SiO2/PVDF, is 159.2°, exhibiting outstanding superhydrophobicity performance. Furthermore, the superhydrophobicity coating also showed satisfactory durability performance in 200 g load wear test after 50 cycles. Importantly, the superhydrophobic coating displayed promising mechanical durability, chemical stability performance, as well as maintained excellent superhydrophobic properties after being placed in water for 3 weeks, indicating the potential for long-term utilization. In the simulated scale inhibition test, it was found that the synthesized coating can also significantly decrease the deposition rate of CaCO3 and successfully enhance its scale inhibition performance.

A Dynamic Testing Approach for Particulate Erosion–Corrosion for Gas Turbine Coatings

Abstract Particle interactions in engines can be complex phenomena leading to degradation of thermal (TBCs) and environmental barrier coatings (EBCs) meant to protect engine components. Ingestion of particles into the engine can lead to recession of coatings due to particle erosion. Similarly, these particles can become molten, adhere to coatings, and result in thermochemical corrosion of coating materials. Erosion testing is often carried out where particles are injected into a gas stream, accelerated within a nozzle, and impinge on samples. Conversely, most molten particle corrosion testing is often done in static furnaces, which does not capture the dynamic nature of deposition. Nevertheless, these damage mechanisms are often tested separately, and no standard exists to test both erosive/corrosive particle interactions with coating materials under relevant turbine operating conditions. Understanding the synergies of particle interactions is crucial in determining operating lifetimes of potential coating materials. Such considerations emphasize the need for realistic approaches in standardizing particle interaction testing in combustion environments. This study outlines efforts at NASA Glenn's Erosion Burner Rig Facility in improving dynamic erosion/corrosion testing methods by assessing the durability of state-of-the-art (SOA) TBC 7 wt % yttria-stabilized zirconia (7YSZ) as a function of particle deposition rate, burner temperature, and particle size. Calibration data to determine particle deposition rate will be presented, and mass and optical profilometry measurements were utilized to estimate mass/volume loss versus deposition per increment of particulate used. Electron microscopy analyses were then carried out to assess coating damage after testing.

Physics of microscale freeform 3D printing of ice

Ice is emerging as a promising sacrificial material in the rapidly expanding area of advanced manufacturing for creating precise 3D internal geometries. Freeform 3D printing of ice (3D-ICE) can produce microscale ice structures with smooth walls, hierarchical transitions, and curved and overhang features. However, controlling 3D-ICE is challenging due to an incomplete understanding of its complex physics involving heat transfer, fluid dynamics, and phase changes. This work aims to advance our understanding of 3D-ICE physics by combining numerical modeling and experimentation. We developed a 2D thermo-fluidic model to analyze the transition from layered to continuous printing and a 3D thermo-fluidic model for the oblique deposition, which enables curved and overhang geometries. Experiments are conducted and compared with model simulations. We found that high droplet deposition rates enable the continuous deposition mode with a sustained liquid cap on top of the ice, facilitating smooth geometries. The diameter of ice structures is controlled by the droplet deposition frequency. Oblique deposition causes unidirectional spillover of the liquid cap and asymmetric heat transfer at the freeze front, rotating the freeze front. These results provide valuable insights for reproducible 3D-ICE printing that could be applied across various fields, including tissue engineering, microfluidics, and soft robotics.

Multilayer Diamond‐Like Carbon Films on Monocrystalline Diamond

Multilayer films of diamond‐like carbon (DLC) on monocrystalline diamond substrates have been for the first time obtained by plasma‐chemical deposition. Their chemical composition and structural and morphological properties are studied. The DLC individual layers differ in their sp3 carbon content. The multilayer nature of the resulting coatings is confirmed by periodic density modulation on the small‐angle X‐ray reflectometry curve and modulations in the CsC8, CsC6, CsC4 lines on the crater depth profile of secondary ions of elements (secondary ion mass spectrometry). The dependence of the deposition rate of multilayer DLC films on diamond, their composition and properties on the argon additive to the reaction gas mixture, as well as on methane flow, pressure and growth time, are studied.

Beach litter deposition and turnover, effects of tides and weather, and implications for cleanup strategies: A case study in the Lofoten archipelago, Norway

Plastic pollution is ubiquitous in the marine environment. Beach cleanups are considered a cost-effective mitigative measure with generally few negative environmental impacts. Beached litter is not static, however, and may wash back out to sea or be buried, meaning it is only temporarily available for cleanup. We studied deposition and turnover of litter on three Arctic beaches in Lofoten, Norway, biweekly for 31 months. The mean estimated daily deposition rate was 10 items/100 m, with a median residence time of 99 days. Both processes were impacted by seasons and weather and varied both spatially and temporally. Strong winds during the fall increased litter influx and onshore winds contributed to its loss. Heavier objects and those higher on the beach persisted longer yet were still subject to turnover. Snow temporarily buries litter but protects it in the long run. Given the turnover of litter, frequent (albeit smaller) cleanups can readily remove 3–4 times more litter from circulation in the environment than larger, infrequent cleanups. With limited resources, it is recommended to prioritise late fall cleanups.

In vitro evaluation of flow diverter performance using a human fibrinogen-based flow model.

Fibrin deposition represents a key step in aneurysm occlusion, promoting endothelization of implants and connective tissue organization as part of the aneurysm-healing mechanism. In this study, the authors introduce a novel in vitro testing platform for flow diverters based on human fibrinogen. A flow diverter was deployed in 4 different glass models. The glass models had the same internal parent artery (4 mm) and aneurysm (8 mm) diameters with varying parent artery angulations (paraophthalmic, sidewall, bifurcation, and slightly curved models). The neck size and area were 4 mm and 25 mm2, respectively. Human fibrinogen (330 mg/dl) was circulated within the glass models at varying flow rates (0, 3, 4, and 5 ml/sec) with or without heparin, calcium chloride, and thrombin for as long as 6 hours or until complete fibrin coverage of the flow diverter's neck was achieved. Aneurysm neck coverage was defined as macroscopic fibrin deposition occluding the flow diverters' pores. Flow characteristics after flow diverter deployment were assessed with computational fluid dynamics analysis. The effects of flow rates, heparin, calcium chloride, and thrombin on fibrin deposition rates were tested using 1-way ANOVA and the Tukey test. A total of 84 replicates were performed. Human fibrin did not accumulate on the flow diverter stents under static conditions. The fibrin deposition rate on the aneurysm neck was significantly greater with the 5 ml/sec flow rate as compared to 3 ml/sec for all models. The paraophthalmic model had the highest inflow velocity of 48.7 cm/sec. The bifurcation model had the highest maximum shear stress (SS) and maximum normalized shear stress values at the device cells at 843.3 dyne/cm2 and 35.1 SS/SSinflow, respectively. The fibrin deposition rates of the paraophthalmic and bifurcation models were significantly higher than those of sidewall and slightly curved models for all additive or flow rate comparisons (p = 0.001 for all comparisons). The incorporation of thrombin significantly increased the fibrin deposition rates across all models (p = 0.001 for all models). Rates of fibrin deposition varied widely across different configurations and additive conditions in this novel in vitro model system. Fibrin accumulation started at the aneurysm inflow zone where flow velocity and shear stress were the highest. The primary factors influencing fibrin deposition included flow velocities, shear stress, and the addition of thrombin at a physiological concentration. Further research is needed to test the clinical utility of fibrinogen-based models for patient-specific aneurysms.

Effect of Hydrophobic Dust Particles on the Evaporation Rate from Water Surface

In the paper, the effect of natural dust deposited from the air on the evaporation rate from the water surface is experimentally investigated. Experiments were conducted for stationary liquid without wind blowing across the surface and with mild wind that does not deform the surface, at a constant rate of particle deposition. It is shown that the evaporation rate is a linear function of the difference in the saturated vapor pressure at the water surface and the partial pressure of the air mixture at the temperature and relative humidity in the laboratory at the beginning of the deposition process, when the proportion of the surface covered with dust is small. With the increase in deposition time, hydrophobic particles gather into conglomerates, reducing the proportion of the exposed surface and the evaporation rate.

A Microporous Channel Copper Immersion Layer Promotes the Rapid Ni-P Electroless Plating Process on Aluminum Alloys at Medium and Low Temperatures

Abstract Electroless plating is a commonly used method to enhance the corrosion resistance, wear resistance, and decorative performance of aluminum alloys. However, in electroless plating processes, it is customary to maintain the solution temperature at levels exceeding 85°C, a critical condition that ensures a sufficiently rapid deposition rate and thereby fosters the formation of high-performance coatings. Conventional immersion pretreatments with zinc and palladium result in lower deposition rates at low temperatures. This study shows that a copper immersion layer with microporous channels can facilitate the electroless plating process for aluminum alloys at lower temperatures. Through a redox reaction in a Cu2+-containing solution at 70°C, a copper immersion layer with a microporous structure could be created on an aluminum alloy. The microporous channels between the copper immersion layer and the aluminum alloy create electrochemical corrosion cells in the plating solution, accelerating the electroless plating process. The Ni-P coating obtained after pretreatment by copper immersion has a higher hardness (578 HV) and a lower corrosion current density (0.55 μA/cm2). This work provides a practical method to rapidly fabricate high-performance Ni-P coatings at intermediate temperatures (70-75°C).

Identification and Derivation of Emerging Contaminants in the Roof Rainwater Confluence

To identify emerging contaminants （ECs） in rainwater is a topic that has gradually received widespread attention. Rainwater resources, specifically urban roofs, play a crucial role in utilizing rainwater efficiently by understanding the occurrence and migration characteristics of pollutants in precipitation. This study selected a typical roof and studied the differences in rainwater quality and pollution occurrence at different collection stages during six rainfall events from March to May in 2023. Principal component analysis （PCA） and correlation analysis were used to explore the distribution, migration, and transformation of ECs in the collection process of roof rainwater. The findings revealed the presence of 44/54 ECs in wet deposition, dry and wet deposition, and roof runoff processes, with a total concentration range of 63.0 to 432.4 ng·L-1 and an average concentration of 166.8 ng·L-1. Notably, bisphenol A （BPA） exhibited the highest concentration, ranging from 14.7 to 265.6 ng·L-1, with an average concentration of 62.5 ng·L-1, followed by ofloxacin （OFX） and ethylhexyl methoxycinnamate （EHMC）, with detected concentrations up to 45.5 ng·L-1 and 44.8 ng·L-1. Dissolved organic matter （DOM）, nitrogen pollutants, and particulate matter were important factors affecting the occurrence characteristics of ECs, with a mantel correlation coefficient of up to 0.98 （P<0.01）. Based on the analysis of different rainfall events and collection stages, variations were observed in the accumulation pathways and contribution ratios of different pollutants. The wet deposition exhibited the highest content of ECs in the initial stage, whereas the dry and wet deposition and roof runoff processes displayed higher ECs content in the later stages. Additionally, the average ECs contribution rates of dry and wet deposition to roof runoff were 21.48% and 78.52%, respectively. Due to the influence of roof material and surface roughness retention performance, over 30% of ECs, including pharmaceuticals and personal care products （PPCPs）, endocrine-disrupting compounds （EDCs）, and pesticides, were deposited on the roof during the runoff collection. The results of this research can provide the theoretical foundation and technical support for the identification and control of ECs in urban roof runoff and for the safe storage of rainwater.

Acoustic Signal-Based Defect Identification for Directed Energy Deposition-Arc Using Wavelet Time-Frequency Diagrams.

Several advantages of directed energy deposition-arc (DED-arc) have garnered considerable research attention including high deposition rates and low costs. However, defects such as discontinuity and pores may occur during the manufacturing process. Defect identification is the key to monitoring and quality assessments of the additive manufacturing process. This study proposes a novel acoustic signal-based defect identification method for DED-arc via wavelet time-frequency diagrams. With the continuous wavelet transform, one-dimensional (1D) acoustic signals acquired in situ during manufacturing are converted into two-dimensional (2D) time-frequency diagrams to train, validate, and test the convolutional neural network (CNN) models. In this study, several CNN models were examined and compared, including AlexNet, ResNet-18, VGG-16, and MobileNetV3. The accuracy of the models was 96.35%, 97.92%, 97.01%, and 98.31%, respectively. The findings demonstrate that the energy distribution of normal and abnormal acoustic signals has significant differences in both the time and frequency domains. The proposed method is verified to identify defects effectively in the manufacturing process and advance the identification time.

The Influence of Bias Voltage on the Structure and Properties of TiZrNbMo Coating Deposited by Magnetron Sputtering

TiZrNbMo coatings have been deposited using the direct current pulsed magnetron sputtering method in an argon atmosphere. The synthesis processes have been conducted under various process parameters. The structure (chemical and phase composition) and mechanical properties of the obtained multicomponent coatings are investigated as a function of plasma modulation frequency (10 Hz and 1000 Hz) and substrate bias (0 to −150 V). It is the case that an increase in the substrate bias decreases the deposition rate and alters the coating’s chemical composition. The latter leads to a Ti concentration decrease and a simultaneous increase in Mo and Nb concentrations in the final coating material. X-ray diffraction measurements indicate a single-phase BCC structure, with grain size decreasing as substrate bias increases. This ultimately forms an amorphous–nanocrystalline structure at −150 V. The mechanical properties of the multicomponent TiZrNbMo coatings have been determined using the nanoindentation method. The maximum values of hardness (13.45 GPa) and elastic modulus (188.6 GPa) are achieved at a substrate bias of −150 V. We also show that the minimum elastic modulus (41.8 GPa) is achieved at an intermediate substrate bias of −100 V.

Design of laser-powder coupling for high-speed laser direct energy deposition

High-speed laser direct energy deposition (DED-LB) is developed to enhance deposition efficiency while maintaining build quality, compared to conventional DED-LB. The core of designing high-speed DED-LB involves formulating the laser-powder coupling, through optimizing nozzle structural and deposition process parameters. This study developed an analytical model to delineate the coupling mechanisms between laser beam and discontinuous coaxial powder stream (DCPS) comprised of individual single powder streams (SPSs). A data pretreatment method, involving gray processing, normalization, and renormalization of the thermal images successively, was applied to validate the model. Simulation results indicate that the DCPS spot size and SPS particle temperature distribution are predominantly influenced, respectively, by the nozzle structural and deposition process parameters. Through jointly designing the nozzle structural and deposition process parameters, a high deposition rate of high-speed DED-LB, which is 1.7 times that of conventional DED-LB, was achieved. This paper pioneers a new design methodology for high-speed DED-LB.

The Influence of Bias Voltage on the Structure and Properties of TiZrNbMo Coating Deposited by Magnetron Sputtering

TiZrNbMo coatings have been deposited using the direct current pulsed magnetron sputtering method in an argon atmosphere. The synthesis processes have been conducted under various process parameters. The structure (chemical and phase composition) and mechanical properties of the obtained multicomponent coatings are investigated as a function of plasma modulation frequency (10 Hz and 1000 Hz) and substrate bias (0 to −150 V). It is the case that an increase in the substrate bias decreases the deposition rate and alters the coating’s chemical composition. The latter leads to a Ti concentration decrease and a simultaneous increase in Mo and Nb concentrations in the final coating material. X-ray diffraction measurements indicate a single-phase BCC structure, with grain size decreasing as substrate bias increases. This ultimately forms an amorphous–nanocrystalline structure at −150 V. The mechanical properties of the multicomponent TiZrNbMo coatings have been determined using the nanoindentation method. The maximum values of hardness (13.45 GPa) and elastic modulus (188.6 GPa) are achieved at a substrate bias of −150 V. We also show that the minimum elastic modulus (41.8 GPa) is achieved at an intermediate substrate bias of −100 V.

The Effect of Interlayer Delay on the Heat Accumulation, Microstructures, and Properties in Laser Hot Wire Directed Energy Deposition of Ti-6Al-4V Single-Wall.

Laser hot wire directed energy deposition (LHW-DED) is a layer-by-layer additive manufacturing technique that permits the fabrication of large-scale Ti-6Al-4V (Ti64) components with a high deposition rate and has gained traction in the aerospace sector in recent years. However, one of the major challenges in LHW-DED Ti64 is heat accumulation, which affects the part quality, microstructure, and properties of as-built specimens. These issues require a comprehensive understanding of the layerwise heat-accumulation-driven process-structure-property relationship in as-deposited samples. In this study, a systematic investigation was performed by fabricating three Ti-6Al-4V single-wall specimens with distinct interlayer delays, i.e., 0, 120, and 300 s. The real-time acquisition of high-fidelity thermal data and high-resolution melt pool images were utilized to demonstrate a direct correlation between layerwise heat accumulation and melt pool dimensions. The results revealed that the maximum heat buildup temperature of the topmost layer decreased from 660 °C to 263 °C with an increase to a 300 s interlayer delay, allowing for better control of the melt pool dimensions, which then resulted in improved part accuracy. Furthermore, the investigation of the location-specific composition, microstructure, and mechanical properties demonstrated that heat buildup resulted in the coarsening of microstructures and, consequently, the reduction of micro-hardness with increasing height. Extending the delay by 120 s resulted in a 5% improvement in the mechanical properties, including an increase in the yield strength from 817 MPa to 859 MPa and the ultimate tensile strength from 914 MPa to 959 MPa. Cooling rates estimated at 900 °C using a one-dimensional thermal model based on a numerical method allowed us to establish the process-structure-property relationship for the wall specimens. The study provides deeper insight into the effect of heat buildup in LHW-DED and serves as a guide for tailoring the properties of as-deposited specimens by regulating interlayer delay.

Quartz grain microtextures of Holocene sebkhas sediments in southeast Tunisia: Implications for sedimentary processes and depositional environments

Detrital quartz grains extracted from sebkha sediments in southeastern Tunisia underwent scanning electron microscopy analysis to identify sediment sources and assess the influence of the saline environment on the grains. Core sediments collected from Sebkha el Melah and Sebkha Mhabeul cover the last 5000 and 2000 BP, respectively. The uppermost Unit III, present in both cores, exhibits two distinct facies based on the mechanical microtextures of its quartz grains. The aeolian facies sediments are characterized by quartz grains with rounded outlines, upturned plates, and crescentic percussion marks. In contrast, the fluvial facies sediments are associated with quartz grains featuring subangular outlines, v-shaped percussion cracks, conchoidal fractures. Observations on the quartz grains of the sebkhas suggest multiple transportation and processing events, indicating long-distance transport and rapid deposition rates. The majority of quartz grains appear to originate from the surrounding terrain, reflecting the dynamic geological history of the region. This study delves into the connection between microtexture variations on quartz grain surfaces and specific historical climatic conditions in the sebkhas. By examining geochemical variations along the cores, facies with elevated salt concentrations corresponding to warmer periods reveal extensively weathered quartz grains. This substantial chemical alteration is evident through microtextures such as oriented etch pits, anastomosed dissolution networks and solution crevasses. The profound dissolution has significantly impacted the quartz lattice, resulting in the decomposition of the grains and the formation of "cauliflower" or "spongy" shapes, erasing prior microtextures. Conversely, during less warm periods, quartz dissolution was less severe, thereby preserving microtextures.Sand grain surfaces are notably sensitive to both transport processes and variations in the physicochemical environment. In the hypersaline and confined environments of sebkhas in southeastern Tunisia, potent post-sedimentary processes can obliterate and obscure the original microtextures recorded on grains from previous environments due to highly fluctuating physicochemical conditions.

Thermophoresis-Induced Polymer-Driven Destabilization of Gold Nanoparticles for Optically Directed Assembly at Interfaces.

The limitations of conventional template-based methods for the deposition of nanoparticle assemblies into defined patterns on solid substrates call for the development of techniques that do not require templates or lithographic masks. The use of optically-induced thermal gradients to drive the migration of colloids toward or away from a laser spot, known as opto-thermophoresis, has shown promise for the low-power trapping and optical manipulation of a variety of colloidal species. However, the printing of colloids using this technique has so far not been established. Herein, a method for the optically directed printing of noble metal nanoparticles, specifically gold nanospheres is reported. The thermophoresis of the polymer polyvinylpyrrolidone and gold nanospheres toward a laser spot led to the deposition of nanoparticle aggregates, capable of serving as surface-enhanced Raman scattering substrates. The influence of heating laser power and the concentrations of polymer, salt, and surfactant on the nanoparticle deposition rate and structure of the printed pattern are studied, showing that a variety of conditions can permit printing, suggesting facile generalization to different nanoparticle compositions, sizes, and shapes. These findings will greatly benefit future efforts for directed nanoparticle assembly, and drive applications in sensing, photothermal heating, and relevant applications in biomedicine and devices.

Study of dust deposition pattern in the respiratory tract of dust particles less than 10 μm in size

The turbulent disturbances of airflow at different respiratory intensities influence the deposition characteristics of dust. The dust concentration during inhalation is 62.3% higher than that during exhalation. During the respiratory process, the turbulent disturbance phenomenon in the inspiratory phase has a dominant influence on dust deposition. At a respiratory intensity range of 15–45 L/min, the final deposition of particles is mainly influenced by the inhalation airflow, while in the range of 60–90 L/min it is mainly influenced by the exhalation airflow. Particle size affected the deposition characteristics, with the deposition of 7.07-μm dust greatly affected by airflow conditions, with a variation in the deposition rate of 56.3%. As the particle size increased, particles less than 10 μm were more frequently deposited in the right nasal cavity (which has an open spatial structure) than the left nasal cavity, as well as in the thick and short right bronchus.

Effects of High Dietary Starch Levels on the Growth Performance, Liver Function, and Metabolome of Largemouth Bass (Micropterus salmoides)

In this study, we conducted a 16-week feeding trial to investigate the effects of a high-cassava starch diet on growth performance, liver function, and metabolism in largemouth bass (Micropterus salmoides). We formulated five diets containing varying levels of cassava starch: 12%, 9%, 6%, 3%, and 0% (termed M12, M9, M6, M3, and M0, respectively). We distributed these diets among largemouth bass with the initial body weight of 83.33 ± 0.55 g via an in-pond “raceway” aquaculture system. Our findings suggest that high level (12%) of cassava starch dietary inclusion adversely affected growth performance metrics such as weight gain rate and specific growth rate, along with feed utilization efficiency indicators, including protein efficiency, protein deposition rate, and the apparent digestibility of dry matter and protein. This negative impact was accompanied by a decrease in intestinal amylase activity. Through further transcriptomic analysis, we identified several key genes associated with carbohydrate metabolism, which underwent changes influencing liver function. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed the involvement of these differentially expressed genes (DEGs) in the tricarboxylic acid cycle (TCA cycle). Comparative metabolomics analysis further indicated that the M9 group showed significant enrichment in pathways related to amino acid metabolism and alterations in the levels of metabolites involved in carbohydrate metabolism. In conclusion, our study demonstrates that incorporating up to 9% cassava starch in the diet can enhance growth performance in largemouth bass by stimulating digestive enzyme activities and promoting glucose utilization.

Impact of Process Parameter on the Behavior of Pyrocarbon Deposition in Chemical Vapour Infiltration (CVI)Process

Carbon-carbon composite manufactured by deposition of pyrocarbon (PyC) through chemical vapor infiltration (CVI) has the key issue of being process parametric sensitive which necessitates the detailed study of the effect of process parameters on the rate of PyC deposition. Conventional method of studying the parametric effect by changing one variable at a time keeping the other variables constant has a limitation of more number of experiments and missing the interaction effect among the variables. Here, the effect of process parameters including temperature, pressure, methane gas flow rate, and nitrogen gas flow rate on the mass gain and PyC deposition was studied by Taguchi method, a statistical optimization method, which has the advantage of very few experiments performed at specific pairs of process parameters only. The experiments were performed at three levels of the process parameters. Carbon-Carbon composite material is processed through the CVI process where PyC was deposited on porous carbon fiber preforms at various process conditions as per the Taguchi method. The impact of gas residence time, Reynolds number, Prandtl number, and Peclet number were also investigated. It was observed that the CVI process parameters significantly affect the rate of PyC deposition. Optimized CVI process parameters are essential for achieving a high rate of PyC deposition to reduce the processing time. The findings have revealed that a higher PyC deposition rate arises under high temperatures, pressure, methane gas flow rate, and optimal nitrogen gas flow rate. The effect of the critical interaction of the CVI process parameters on the rate of PyC deposition was also obtained. Based on the experimental studies, process guidelines are proposed for the densification of carbon fibers preform to realize C/C composite products.