Improved Surface Smoothness Research Articles

Correlating FDM printing parameters with mechanical properties and surface quality of PLA printouts

Abstract This study explores the correlation between four critical Fused Deposition Modeling (FDM) parameters—extrusion temperature, layer height, print speed, and infill density—and the mechanical properties and surface quality of PLA (Polylactic Acid) printouts. The mechanical properties, including Young’s modulus, tensile strength, and bending strength, were evaluated alongside surface roughness and dimensional accuracy. The results indicate that extrusion temperatures between 200°C and 220°C optimize mechanical performance, enhancing tensile strength and bending strength, while smaller layer heights (0.1 mm) improve surface smoothness but increase print time. Moderate print speeds (around 60 mm/s) offer the best balance between strength and efficiency, while higher infill densities (above 80%) enhance mechanical properties, increasing both tensile and bending strength by up to 25%. These findings provide key insights into optimizing FDM printing parameters to achieve improved structural integrity and aesthetic quality in PLA prints.

Plasma Etch of IGZO Thin Film and IGZO/SiO2 Interface Diffusion in Inductively Coupled CH4/Ar Plasmas

ABSTRACTIn this work, the etching characteristics of InGaZnO4 (IGZO) thin films were systemically investigated in inductively coupled CH4/Ar plasmas with various gas ratios, bias voltages, and surface temperatures. The ion flux in the CH4/Ar plasmas was analyzed using bias power and voltage, whereas the relative densities of CH and H radicals were quantified through optical actinometry. The change in CH3 radical density was also estimated based on plasma kinetics analysis. The correlations between the plasma properties and IGZO etch rate were investigated. In CH4/Ar plasmas with CH4 ratios below 80%, the IGZO etch rate increases with a higher CH4 proportion, aligning with the ascending trend of CH3 radical density, which suggests that CH3 radical density acts as a limiting factor (radical‐limited regime). However, the IGZO etch rate decreases when the CH4 ratio exceeds 80%, corresponding to the reduction in ion flux, which indicates that ion flux becomes a limiting factor in this ion‐limited regime. The IGZO etch rate shows a linear relationship with bias voltage and follows the Arrhenius equation with varying surface temperature in plasmas without bias voltage. A spontaneous etch model was proposed based on these relationships. In this model, the IGZO etch rate depends on CH3 radical density and IGZO surface reactivity, where ion bombardment contributes more significantly to surface reactivity than high surface temperature. IGZO thin film was deposited on SiO2 during the fabrication of a 3D stacked ferroelectric field‐effect transistor (FeFET) memory device. The interaction between IGZO and SiO2 during CH4/Ar plasma processing was investigated using time‐of‐flight secondary ion mass spectrometry. The efficacy of removing IGZO atoms that had diffused into the SiO2 network was enhanced when subjected to plasma with a bias voltage, compared to the process without a bias voltage. However, exposure to CH4/Ar plasma resulted in a deeper diffusion of IGZO atoms into the SiO2 network, primarily attributed to ion bombardment rather than elevated surface temperature. A significant improvement in surface smoothness was achieved after IGZO and SiO2 etch by introducing BCl3 into the SiO2 etching chemistry.

Increase the efficiency of lead sulfide colloidal quantum dots solar cells by incorporating In2O3 and NiO interlayers

Substantial advancements have been made in PbS colloidal quantum dot solar cells (CQDSCs) by focusing on device architecture, manipulating band alignment, and refining the surface chemistry of colloidal quantum dots (CQDs). Nevertheless, creating an incredibly stable and efficient solar cell remains a challenging problem for researchers in this field. This study reveals that the efficiency of PbS CQDSCs can be improved by incorporating ultrathin In2O3 (between ITO electrode & indium-doped zinc oxide ETL) and NiO (between PbS-EDT HTL and Au electrode) nanocrystalline interlayers. The enhanced power conversion efficiency (PCE), which increases from 11.5 % to 13.6 %, is attributed to the improved surface smoothness and well-matched energy bandgap. Furthermore, following a heating period of 90 min at a temperature of 80 °C and 50 days of storage in the air, the solar cells containing these interlayers retained 98 % and 99 % of their initial efficiency, respectively. In distinction, the control device without these interlayers maintained only 85 % and 91 % of their initial efficiency under identical testing environments.

Atomic-scale understanding of microstructural evolution in electrochemical additive manufacturing of metallic nickel

Atomic-level manufacturing is fundamentally concerned with the precise removal, addition, and migration of material at the atomic and close-to-atomic scale (ACS). Tip-based electrochemical deposition, a quintessential ACS electrochemical additive manufacturing technique, offers promising prospects for achieving bottom-up fabrication of metallic micro/nano structures. However, the complex physicochemical reactions involved in electrodes lead to a limited understanding of the mechanisms underlying atomic electrodeposition and structural evolution. For the first time, this study proposes electric double-layer controlled electrochemical kinetics and investigates the effect of direct current (DC) and pulse current (PC) on nickel atomic electrodeposition using molecular dynamics (MD) simulations. The findings reveal that compared to DC electrodeposition, PC electrodeposition results in more orderly deposition morphology, improved surface smoothness, reduced dislocation density, and lower crystal distortion, with these effects being particularly pronounced under low pulse duty ratio conditions. In addition, the pulse frequency significantly influences the morphology and structure of the deposit. The high pulse frequency yields smoother surfaces with local protrusions, while the low frequency favors the formation of orderly and dense structures excepting slightly increased roughness. This study provides critical insights into understanding the microscopic mechanisms of atomic-scale electrodeposition processes and achieving atomically controlled tip-based electrochemical additive manufacturing of micro/nanodevices.

Ultrathin Carbon Textures Produced on Machined Surfaces in an Integrated Finishing Process Using Microabrasive Films.

This study presents research into the unique method of depositing carbon layers onto processed surfaces, during finishing with abrasive films, on a global basis. The authors of this article are holders of the patent for this method. What makes this technology outstanding is that it integrates processes, whereby micro-finishing and the deposition of a carbon layer onto freshly exposed surface fragments is achieved simultaneously, in a single process. Among the main advantages accruable from this process is the reduction of surface irregularities, while the deposition of a carbon layer is achieved simultaneously. Ultrathin graphite layers can be widely used in conditions where other methods of reducing the coefficient of friction are not possible, such as in regard to micromechanisms. This article illustrates the application of carbon coating, end on, on a surface processed with abrasive film, containing intergranular spaces, saturated with graphite. Thin carbon layers were obtained on two substrates that did not contain carbon in their initial composition: soda-lime glass and a tin-bronze alloy. It was performed through microscopic examinations of the produced surface, roughness analyses of these surfaces, and analysis of the chemical compositions determined by two methods, namely EDS and GDOES, proving the existence of the coatings. The aim of this paper is to prove the possibility and efficiency of using graphite-impregnated lapping films in the deposition process of carbon films, with improved surface smoothness, durability, and wear resistance. The produced coatings will be tested in regard to their operational properties in further research. The authors underline the potential of this method to revolutionize surface treatment processes, due to the significant advantages it offers across various industries.

Characteristics of corn starch/polyvinyl alcohol composite film with improved flexibility and UV shielding ability by novel approach combining chemical cross-linking and physical blending

With the aim of effectively improving the performance of bio-friendly food packaging and circumventing the hazards associated with petroleum-based plastic food packaging, composite films of corn starch and polyvinyl alcohol were prepared using a new method that involved chemical cross-linking of glutaraldehyde and blending with cinnamon essential oil nanoemulsion (CNE). Glutaraldehyde and CNE enhance the film's network structure by chemical bonding and hydrogen bonding, respectively. This results in improved surface smoothness, mechanical properties, and UV shielding ability of the film. However, the films' surface hydrophilicity increased as a result of CNE, which is harmful for food preservation in high humidity. Overall, glutaraldehyde and CNE have a synergistic effect on some of the properties of the film which is mainly attributed to the films' structure improvement. The films have great potential for preparing flexible and UV-shielding films and offer new ideas for developing biodegradable films.

A Review: Nanofluids in Machining for Performance and Sustainability

This study examines the use of hybrid and normal nano cutting fluids in drilling, a process commonly used by sectors of the economy that normally depend on gulf cut or dry cut oil. These lubricants work well for drilling, but they don’t improve surface smoothness enough and might shorten the tools lifespan. In order to mitigate these problems, scientists are investigating nanofluids as an alternative to conventional lubricants. They are experimenting with different mixtures of nanofluids as a foundation in drilling operations. Multiple investigations demonstrate that the utilization of nanofluid as cutting fluid can improve lubrication as well as cooling in comparison to conventional cutting fluids. Various drilling techniques, such as dry machining, minimum quantity of lubrication, and solid lubricant, are employed however literature suggests that MQL is the most environmentally friendly option. Given that drilling involves working on tough surfaces, it is imperative to have a high-quality coolant lubricant. While there are several choices available for base lubricants, none of them can achieve the required level of surface finish during drilling. As a possible lubricant option in the future, the research suggests using a hybrid nanofluid in combination with multiple base lubricants.

Investigation on surface roughness of ultrasonic assisted vapour smoothing of acrylonitrile butadiene styrene printed sample

Additive manufacturing offers many benefits, yet it is confronted with the challenge of rough surfaces resulting from the appearance of seam lines on the printed parts due to the layer-by-layer printing process. This study investigates the effect of ultrasonic-assisted vapor smoothing on the surface roughness of 3D-printed ABS samples. The ABS samples were printed with an open-source FDM printer. The vapour smoothing process was conducted by applying acetone and altering the ultrasonic frequencies and times to 0 kHz, 10 kHz, and 20 kHz for the frequencies and 10 min, 20 min, and 30 min for the times. The surface roughness measurements were performed using a Mitutoyo SJ-301 surface roughness tester. The findings demonstrated enhancements in the quality of the surface, reduction in the visibility of layer lines, and improved surface smoothness for all the samples. From the ANOVA analysis, the average value of Ra for 30 kHz frequency is 2.57 μm, which is better than 3.19 μm for 10 kHz frequency. The manipulation of ultrasonic frequencies and exposure durations decreased surface roughness parameters, suggesting enhancement of the time to attain smoother surfaces. This work demonstrates the effectiveness of ultrasonic-assisted vapour smoothing as a feasible post-processing technique for enhancing surface quality in 3D-printed ABS-printed parts.

Lei's formula attenuates osteoarthritis mediated by suppression of chondrocyte senescence via the mTOR axis: in vitro and in vivo experiments.

Lei's formula (LSF), a traditional Chinese herbal remedy, is recognized for its remarkable clinical effectiveness in treating osteoarthritis (OA). Despite its therapeutic potential, the exact molecular mechanisms underlying LSF's action in OA have remained enigmatic. Existing research has shed light on the role of the mTOR signaling pathway in promoting chondrocyte senescence, a central factor in OA-related cartilage degeneration. Consequently, targeting mTOR to mitigate chondrocyte senescence presents a promising avenue for OA treatment. The primary objective of this study is to establish LSF's chondroprotective potential and confirm its anti-osteoarthritic efficacy through mTOR inhibition. In vivo assessments using an OA mouse model reveal substantial articular cartilage degeneration. However, LSF serves as an effective guardian of articular cartilage, evidenced by reduced subchondral osteosclerosis, increased cartilage thickness, improved surface smoothness, decreased OARSI scores, elevated expression of cartilage anabolic markers (Col2 and Aggrecan), reduced expression of catabolic markers (Adamts5 and MMP13), increased expression of the chondrocyte hypertrophy marker (Col10), and decreased expression of chondrocyte senescence markers (P16 and P21). In vitro findings demonstrate that LSF shields chondrocytes from H2O2-induced apoptosis, inhibits senescence, enhances chondrocyte differentiation, promotes the synthesis of type II collagen and proteoglycans, and reduces cartilage degradation. Mechanistically, LSF suppresses chondrocyte senescence through the mTOR axis, orchestrating the equilibrium between chondrocyte anabolism and catabolism, ultimately leading to reduced apoptosis and decelerated OA cartilage degradation. LSF holds significant promise as a therapeutic approach for OA treatment, offering new insights into potential treatments for this prevalent age-related condition.

Synthesis, characterization, and corrosion protection potential of a highly effective and water‐miscible surfactant for mild steel in sulfuric acid solution

AbstractIn the current study, a tetracationic quaternary ammonium salt (TCQAC) was synthesized and characterized and its ability to suppress corrosion on mild steel (MS) in a 0.5 M H2SO4 solution was examined. Various chemical, electrochemical, and surface characterization techniques were utilized to study the inhibition efficiency of TCQAC. The TCQAC manifests 99.83% efficiency at 20 ppm concentration. Out of all the examined isotherm models, the Langmuir isotherm offered the best fit for the TCQAC adsorption on the MS surface. A very high negative value of ΔGads (−45.18 kJ mol−1) suggests that the adsorption of TCQAC followed the chemisorption mechanism. Electrochemical studies indicate that TCQAC increases the linear and charge transfer resistances (LPR and Rct, respectively). TCQAC slows down the anodic and cathodic Tafel reactions; however, it acts as an anodic‐type inhibitor at 5, 10, and 20 ppm. The appearance of extra Cl and N signals in the energy dispersive x‐ray (EDX) spectrum and an improvement in surface smoothness in the scanning electron microscope (SEM) image of the inhibited sample corroborated the adsorption method of corrosion inhibition. X‐ray photoelectron spectroscopy (XPS) study indicates that TCQAC creates corrosion preventive layers by chemical adsorption. In Frontier molecular orbitals (FMOs), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were delocalized around the central part that comprises two benzyls, four allyls, and one hydrocarbon ((CH2)6) moieties and two quaternary nitrogen atoms. The outcomes of XPS and density functional theory (DFT) analyses indicate that the chemisorption of TCQAC occurs by dπ–pπ bonding with the surface iron atoms. The π‐electrons of aryl and allyl moieties extensively participate in the bonding.

Study of short-wavelength pass dichroic laser mirror coatings with hafnia–silica mixture layers

Hafnia/silica (HfO2/SiO2) short-wavelength pass dichroic laser mirror (DLM) coatings are widely utilized in high-power laser systems. However, the half-wave hole effect resulting from the refractive index inhomogeneity of HfO2 severely restricts the spectra and potential applications of these coatings. To address this issue, an investigation was conducted on HfO2–SiO2 mixture coatings with different proportions, which were produced by electron beam co-evaporation. Compared to the inhomogeneous growth characteristics observed in pure HfO2 coatings, the introduction of 10 % or higher SiO2 admixing in HfO2–SiO2 mixture coatings results in an amorphous structure characterized by excellent refractive index homogeneity and improved surface smoothness. Leveraging this, different DLM coatings with the objective of achieving high transmittance across the 400 to 900 nm range were designed and prepared, while ensuring high reflectance at 1064 nm. The incorporation of HfO2–SiO2 mixture layers instead of pure HfO2 layers in the mirror coatings led to a fundamental inhibition of the half-wave hole effect throughout the entire broad transmission band, resulting in a substantial improvement in the optical performance of the coatings. Moreover, by incorporating several types of HfO2–SiO2 mixture layers with different proportions in the coating stacks, the transmittance of DLM coatings in the pass band can be further increased, and the transmission fluctuations at different wavelengths can be further compressed. Additionally, compared to traditional DLM coatings with HfO2 layers, DLM coatings incorporating HfO2–SiO2 mixture layers exhibit lower roughness, higher laser-induced damage threshold (LIDT) at 532 nm, and similar LIDT at 1064 nm. These results indicate a promising strategy for fabricating DLM coatings tailored for high-power laser systems.

In Vitro and In Vivo Characterisation of Lactiplantibacillus plantarum LAB12 in Pea Protein-Alginate Microcapsules.

The susceptibility of probiotics to high temperature and low pH remains a major challenge in food industries. Numerous commercially available probiotic products were reportedly presented with lower probiotic viability than claimed. To confer health benefits to the host, it is essential that probiotic strain remains viable at optimal amount during food processing procedures, storage and passage through the gastrointestinal tract. This study addressed these issues by immobilising Lactiplantibacillus plantarum LAB12 isolated from tempeh (fermented soybean) in a polymeric matrix made up of alginate (Alg, 0.5% w/v) and denatured pea protein isolate (PPi, 1-10% w/v) using the emulsion/acidification technique. Alg supplemented with 10% PPi (Alg-PPi10) appeared to be optimally small (< 350µm), substantiated by the improved surface smoothness and uniform dispersion of probiotics in the Alg-PPi core. The findings indicated that microencapsulation enhanced thermal stability of L. plantarum LAB12. The microencapsulated L. plantarum LAB12 remained highly viable (80%) despite exposure to 100 °C for 5min. The microencapsulated cell number during storage at 4 and 25 °C for 8weeks was greater than 7 log CFU g-1. L. plantarum LAB12 encapsulated in Alg-PPi10 exhibited high viability (96%) in simulated gastric juice (at pH 1.8 for 120min) and facilitated maximum release of probiotics (> 9 log CFU g-1) in simulated intestinal fluid (at pH 6.8 for 240min). Whilst retaining their intrinsic cholesterol lowering effect, microencapsulation conferred additional advantages to L. plantarum LAB12 in terms of lowering serum triglyceride and increasing HDL cholesterol in zebrafish fed with high-cholesterol diet (HCD). Overall, our findings strongly imply the potential use of Alg-PPi10 as an effective medium that confers thermal protection and facilitates pH-sensitive release of cholesterol-reducing L. plantarum LAB12. This will allow the diverse applications L. plantarum LAB12 across health, food and agro-feed industries amongst others.

Improving surface smoothness in FDM parts through ironing post-processing

Additive manufacturing using fused deposition modelling (FDM) is an affordable and efficient way to produce functional parts and prototypes. However, the FDM-manufactured parts, particularly those made of polylactic acid (PLA), has some drawbacks regarding accuracy and surface finish. To address this, post-processing techniques such as ironing can be applied. However, little is known about the effect of ironing process parameters on surface roughness, and there is a lack of comparative studies on contact and non-contact measurement methods. This study aims to address these gaps by investigating the impact of path speed, ironing spacing, and flow rate on the surface roughness of FDM-produced PLA samples using both contact and non-contact measurement methods. The results show that the ironing process can lead to a significant reduction in surface roughness values, and careful optimization of process parameters can further minimize roughness. The study highlights the advantages and limitations of contact and non-contact methods for surface roughness analysis and provides guidance on selecting the appropriate method for a given application and material.

Fast-tool-servo-controlled shear-thickening micropolishing

Polishing-based post-processing is essential for removing the undesired surface diffraction on diamond-turned microstructured surfaces that is enhanced by periodic tool marks. To overcome challenges in existing micropolishing methods, a fast-tool-servo-controlled shear-thickening micropolishing method was proposed for the non-contact and controllable polishing of microstructured surfaces. The operating kinematics and material removal mechanism are modeled analytically and investigated experimentally. The comprehensive principal stress in front of the rake face of the tool is found to mainly contribute to the material removal. The fast tool servo can tune the principal stress and the viscosity of the slurry by flexibly adjusting the gap width between the surface and the tool edge. Thus, the material removal can be controlled at any operating position. Meanwhile, although the material removal rate is nonlinearly related to the rotation radius and gap width, the constraint between these two factors is linear for achieving a fixed material removal rate. Finally, the feasibility of the proposed micropolishing method is demonstrated by successfully polishing rotationally symmetric and asymmetric microstructured surfaces to achieve improved surface smoothness and conformal surface shapes.

Experimental Study of the Impact of Various Bio Based Cutting Fluid Using Multiple Machining Characteristics during Shaping Operation

In machining, the use of cutting fluids in metal machining has several benefits, including increased tool life, less thermal deformation of the work piece, improved surface smoothness, and flushing away of chips from the cutting zone. - Three distinct vegetablebased cutting fluids, such as rice bran oil, almond oil, and sunflower oil, were used in this study to measure the surface roughness during shaping operations. Mild steel, stainless steel, and EN 8. Vegetable cutting oils have been studied for their potential to enhance surface finish during shaping at various speeds and feed rates. Speed, feed rate, and depth were taken into account as machining parameters in the trials. Cutting fluids; cutting fluids made from vegetables. Feed rate, speed, and depth of cut are all different cutting characteristics that are taken into account. Experimental research into surface roughness values is done after the three components are machined using various settings.

In Vitro Evaluation of the Shading Effect of Various Zirconia Surface Stains on Porcelain Crowns

Human teeth display various colors under natural light. Dental restorations, such as zirconia crowns, are generally used to rehabilitate the oral function of patients with tooth loss due to trauma or natural tooth falls. However, significant improvements in the color and translucency of zirconia are required to meet the clinical needs for dental restoration. In the past, a large amount of ceramic powder has been used to improve the appearance of zirconia. However, the interface between the ceramic powder and zirconia makes them prone to falling off. Therefore, the aesthetics of zirconia crowns remains a major challenge. Recently, substantial advances have been made in the field of dental materials, as special staining agents for zirconia have been introduced as alternatives to ceramic powders. Therefore, this study tested zirconia-specific staining agents that were used to produce zirconia samples with A1 and A3 colors. A dental colorimetric plate was used as the control group to assess the staining effects of the different brands of staining agents. Meanwhile, two hypotheses were proposed: that the staining effects of these special staining agents for zirconia met the criteria for clinical application and that there was no significant difference between the different staining agents for zirconia. The results showed that the coatings of different brands of staining agents were ultrathin, with a thickness of approximately 27–78 µm. In addition, the coloring effects of the zirconia staining agents were not significantly different from those of the colorimetric plates. After staining, the zirconia samples had decreased surface roughness and contact angle values, which improved surface smoothness and cleanliness. In summary, the results support the hypothesis of this study that zirconia stains can be used as an alternative to the current fabrication methods for clinical dental restorations. We sought to identify the clinical techniques that are easier to perform and to overcome the current problem of dental technicians requiring considerable dentin space for staining. It is expected that the results of this study will be useful in clinical dental restorations.

Investigation of 3‐aminopropyltrimethoxysilane for direct deposition of thin films containing primary amine groups by open‐air plasma jets

AbstractOpen‐air plasma jets are becoming increasingly popular due to easy and affordable large‐scale coating deposition on diverse substrates. However, direct deposition of primary amine groups (NH2), which are attractive as covalent anchor points for molecule grafting, remains challenging. In this study, 3‐aminopropyltrimethoxysilane (APTMS) has been directly polymerized on glass by a plasma jet. Quantification of NH2 showed that APTMS polymerization and NH2 degradation were correlated with Yasuda's parameter and that a compromise between NH2 retention and coating stability is required. Evaporation of APTMS was found to improve surface smoothness and homogeneity but was found to decrease the deposited NH2 concentration, from 3.7 ± 1.3 NH2/nm2 to three times lower. Results showed that deposited NH2 could be used as anchor points for polyethylene glycol chain immobilization.

Elastomeric Foldable and High-Temperature Endurance Porous Graphene Films with Superior Electromagnetic Interference Shielding Performance

Materials possessing multiple features of ultrathinness, flexibility and foldability, high-temperature resistance, and superb electromagnetic interference shielding performance are urgently needed for future portable and wearable electronics. Herein, highly flexible, robust, and porous graphene films (GFs) are controllably fabricated via a strategically combined chemical reduction with a rapid confined foaming approach. The spatially confined foaming at 500 °C in air endows the annealed GFs (AGFs) with integrated functionalities including a significantly improved surface smoothness, a lower sheet resistance, an elevated high-temperature endurance, a tailored hierarchical porous architecture, and elimination of iodine doping synchronous impurities. The resultant AGFs exhibit an excellent self-recovering elastic property, outstanding reliability during a large number of repetitive bending cycles, and remarkable flexibility and mechanical strength. More laudably, compared to the shielding effectiveness (SE) of GFs fabricated by individual HI reduction (28.63 dB) and thermal reduction (19.37 dB), the AGFs present a greatly improved SE up to a superior level of 48.37 dB due to the enhanced absorption of microwaves in the well-constructed highly conductive and hierarchical porous structure. Therefore, such thin AGFs possessing excellent flexibility and elasticity and high-temperature durability associated with superb shielding performance offer strong potential applications in the field of portable and wearable devices.

New Eco-Friendly Coating Formulations to Improve Strength and Physical Properties of Recycled Paper Boards for Sustainable Packaging Applications

This research work emphasizes the applicability of eco-friendly clay-based coating formulation on recycled paperboards to improve strength properties. Two new clay-based coating formulations were prepared using china clay (F1) and montmorillonite clay (F2) as the main constituents and acronal, sorbitol, and ammonia as other additives. The coating was performed using K bar coater at three different thicknesses (4, 10, and 15 μm). The strength and physical properties of recycled paperboard coated with formulations F1 and F2 were compared. It was found that the strength properties of recycled paperboards coated with formulation F1 were higher, and the physical properties (porosity and cobb) were lower than formulation F2. Scanning electron microscopy (SEM) analysis indicated reducing pores and unevenness on the surface of recycled paperboards when coated with formulation F1. The atomic force microscopy (AFM) images of the recycled paperboards coated with formulation F1 revealed improved surface smoothness for a coating thickness of 4 μm.

Synergistic friction-reducing and anti-wear behaviors of DLC on NCD films via in-situ synthesis by fs laser ablation

In present work, diamond-like carbon (DLC) films are in-situ synthesized on nano-crystalline diamond (NCD) films via femtosecond laser ablation (FLA). Field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and nano-indentation are performed to characterize the as-fabricated DLC/NCD composite films. The tribological performance of as-fabricated DLC/NCD composite films is investigated by ball-on-plate reciprocating friction tests with zirconia bio-ceramic (ZBC) balls as counterparts under simulated body fluid (SBF) lubrication. For comparison, as-grown micro-crystalline diamond (MCD) films and NCD films are also tested. The stable friction coefficient of MCD, NCD and DLC/NCD films is 0.163 ± 0.018, 0.082 ± 0.017 and 0.051 ± 0.016, respectively. Besides, all three types of sample exhibit excellent and close wear resistance, while the wear rate of ZBC counterparts for MCD, NCD and DLC/NCD films varies, which is about 6.59 × 10−8, 1.33 × 10−8 and 1.21 × 10−9 mm3/Nm, respectively. The results show that the DLC/NCD composite films can significantly lower the stable friction coefficient and the amount of wear debris, which is attributed to the lubrication effect and improved surface smoothness by DLC top-layers. On the other hand, much higher stable friction coefficient and greatly increased wear debris can be observed for the MCD and NCD films, which is ascribed to their much rougher surfaces.