High Roughness Research Articles

Evaluation of the wear-resistance of DLC-coated hard-on-soft pairings for biomedical applications

Diamond-like carbon (DLC) coatings deposited on the articulating surfaces of total hip or knee arthroplasties have the potential to enhance the overall biotribological behavior and longevity. In this contribution, we employ an ultrahigh molecular weight polyethylene ball-on-three cobalt chromium or titanium alloy pin configuration lubricated by simulated body fluid to effectively carry out screening tests. Thus, the influence of the choice of the coated component (metallic and/or polymeric) as well as the differences between a higher and lower load case with non- and conventionally cross-linked polyethylene were studied. The studied coating systems featured excellent mechanical properties with a substantial enhancement of indentation hardness and elastic modulus ratios. The adhesion of the coatings as determined in modified scratch tests can be considered as very good to polymeric and as satisfactory to metallic substrates, thus confirming the potential for the use in total joint arthroplasties. Although the coatings predominantly led to an increase in friction due to the considerably higher roughness, wear was substantially reduced. While only the metallic components were mostly coated in studies reported in literature, our investigation showed that a coating of the polymer component in particular is of decisive importance for enhancing the wear performance and increasing the service life of load-bearing implants. Moreover, single sided coating results in higher wear of the uncoated counter-part. Therefore, coating systems deposited on both articulating surfaces, polymeric and metallic, should be pursued in the future.

The Effect of a Duplex Surface Treatment on the Corrosion and Tribocorrosion Characteristics of Additively Manufactured Ti-6Al-4V

The use of additively manufactured components specifically utilizing titanium alloys has seen rapid growth particularly in aerospace applications; however, the propensity for retained porosity, high(er) roughness finish, and detrimental tensile surface residual stresses are still a limiting factor curbing its expansion to other sectors such as maritime. The main aim of this investigation is to determine the effect of a duplex treatment, consisting of shot peening (SP) and a coating deposited by physical vapor deposition (PVD), to mitigate these issues and improve the surface characteristics of this material. In this study, the additive manufactured Ti-6Al-4V material was observed to have a tensile and yield strength comparable to its wrought counterpart. It also exhibited good impact performance undergoing mixed mode fracture. It was also observed that the SP and duplex treatments resulted in a 13% and 210% increase in hardness, respectively. Whilst the untreated and SP treated samples exhibited a similar tribocorrosion behavior, the duplex-treated sample exhibited the greatest resistance to corrosion-wear observed by the lack of damage on the surface and the diminished material loss rates. On the other hand, the surface treatments did not improve the corrosion performance of the Ti-6Al-4V substrate.

Mechanical behaviors of coral sand and relationship between particle breakage and plastic work

As a special geotechnical material, coral calcareous sand (CCS), also widely known as coral sand or calcareous sand, surely has similarities and differences in mechanical behaviors with terrigenous sand. As the foundation material of some important structures such as ports, aircraft runways, and marine lighthouses in the South China Sea (SCS), it is necessary and has engineering significance to study its basic mechanical properties. Taking the CCS sampled from a reclaimed land on the top of a natural coral reef in the SCS as the typical case, a series of drained and undrained triaxial shear tests were performed under conventional and high confining pressure in this study. It is found that CCS has all the characteristics that all granular materials should have. However, since the irregular particle morphology and high roughness particle surface, CCS presents a great initial shear stiffness which is significantly different from that of quartz sand. Only some CCS specimens can strictly reach the critical state, and the feature lines in the p’-q space, i.e., critical state line, and phase transformation line are not affected by the factors such as the consolidation confining pressure, initial dry density, and drainage condition. However, the critical state line in the e-lnp’ space is not unique, but dependent on the initial dry density. Based on the particle breakage measurement, a new description for the relationship between particle crushing and plastic work is proposed. It could provide an experimental basis for the development of a constitutive model considering the particle breakage for CCS.

Effect of surface treatment on flexural strength and subcritical crack growth of lithium disilicate: an in vitro study

Alternative surface treatments have been proposed for the cementation of lithium disilicate ceramics aiming to improve adhesive and flexural strength under fatigue. This study aimed to evaluate the slow crack growth (SCG) parameters of the lithium disilicate ceramic after hydrofluoric acid (HF) etching or air abrasion (AB) as surface treatments. Ceramic discs were treated with HF (5%, 20 s) or AB (30 µm silica-modified alumina particles, 2.8 bar, 10 mm distance, 15 s), and received a layer of resin cement. The surface roughness after surface treatment was evaluated (n = 5). Samples were tested in a piston-on-three-ball assembly to evaluate the flexural strength (n = 20), inert strength (n = 25), and to determine SCG parameters n and D (n = 35). The highest roughness (p < 0.01) was observed in the AB group, with the highest reliability according to the Weibull analysis, but the lowest SCG susceptibility. Flexural (p = 0.03) and inert strength (p < 0.01) were the greatest in the HF group. Despite exhibiting lower strength than 5% HF, air abrasion may be an alternative for the surface treatment of lithium disilicate surfaces, indicating the best prognosis over time.

Tensile and axial fatigue properties of AISI 316 L stainless steel fabricated by materials extrusion additive manufacturing

Herein, the surface quality, physical, microstructural, tensile and axial fatigue properties of 316 L stainless steel fabricated by materials extrusion additive manufacturing (MEX) are investigated and compared to the well-established and similar fabrication process, metal injection moulding (MIM). The results reveal no discernible difference in microstructure, preferential orientation and grain size between MEX and MIM parts, except for voids between deposited paths found in MEX parts, and Si-O inclusions in MIM parts. MEX parts have slightly higher tensile properties than MIM parts due to the higher relative sintered density. However, the endurance limit of MEX parts is lower than MIM. This is attributed to differences in the surface characteristics, in which MEX parts have layer-by-layer characteristics, higher roughness and Al2O3 contamination from the separator. They sensitively act as crack origination sites and result in lower fatigue resistance when compared to MIM.

Anti-Wetting Performance of an Electrospun PVDF/PVP Membrane Modified by Solvothermal Treatment in Membrane Distillation

Membrane distillation (MD) is attractive for water reclamation due to the fact of its unique characteristics. However, membrane wetting becomes an obstacle to its further application. In this paper, a novel hydrophobic polyvinylidene fluoride/poly(vinyl pyrrolidone) (PVDF/PVP) membrane was fabricated by electrospinning and solvothermal treatment. The electrospun membranes prepared by electrospinning showed a multilevel interconnected nanofibrous structure. Then, a solvothermal treatment introduced the micro/nanostructure to the membrane with high roughness (Ra = 598 nm), thereby the water contact angle of the membrane increased to 158.3 ± 2.2°. Owing to the superior hydrophobicity, the membrane presented high resistance to wetting in both NaCl and SDS solutions. Compared to the pristine PVDF membrane, which showed wetting with a flux decline (120 min for 0.05 mM surfactant solution treatment), the prepared membrane showed outstanding stability over 600 min, even in 0.2 mM surfactant solutions. These results confirm a simple method for anti-wetting hydrophobic membrane preparation, which presented universal significance to direct contact membrane distillation (DCMD) for industrial application.

Solvent effect on structural and optical properties of Titania nanoparticles for pH sensing applications

Herein, solvents i.e., methanol, ethanol, propanol, and butanol-assisted titania nanoparticles (TNPs) are synthesized by low-temperature sol-gel method for pH sensing applications. The influence of solvent on the morphology, roughness, porosity, refractive index, and sensing properties are investigated. The relatively high average roughness 2.5 nm and lower refractive index 1.69 is observed for B-TNPs. The sensitivity of butanol-assisted phenol red encapsulated TNPs is observed 2.32 counts/pH.

The Orientation and High-Quality Effect of Deposit Layer to Surface Roughness on FDM 3D Printed Part

In 3rd revolution industry, additive manufacturing has a role in term manufacturing process for creating a part. Additive manufacturing has popular name that is called 3D printing technology. The surface quality of 3D printed part is still observed and developed. So, the purpose of research is to know the surface quality of 3D printed part to different layer height and orientation of deposit layer in Polylactic Acid material (PLA). The experimental test involved a 3D printer machine to build square 3D printed part. Furthermore, the quality surface of specimen is measured by using SurftestSJ-301 Mitutoyo device. The layer height of the test specimen is varied from 0.05 mm to 0.15 mm with the increment of 0.5 mm for each specimen. The layer angle of deposit material is also varied from 45o to 90o with the increment of 15o for each variation. Base on the observation and analyzation, the highest roughness is on the Lh 0.15 mm (11.79 ) with 45o of layer angle of deposit material, whereas the lowest roughness on the Lh 0.05 mm (0.98 ) with 90o of layer angle of deposit material.

Experimental cyclic behavior of concrete interfaces with postinstalled reinforcing bars or alternative connectors

AbstractIn this experimental campaign, concrete‐to‐concrete interfaces were examined under cyclic actions, crossed by postinstalled reinforcing bars or industrial steel screws. In addition, the effect of the embedment length and the roughness was investigated. It was observed that different failure modes occur, depending on the different connector types and embedment depths. The positive effect of roughness on the interface resistance was confirmed, but the results indicate that, for very high roughness values, the resistance may be smaller than for moderate values. It was also noticed that the behavior of interfaces crossed by mechanical anchors was less stiff in the ascending branch and exhibited a less steep falling branch. The extension of the project on testing thin overlays showed that the resistance was significantly affected in case of cyclic loading, suggesting that the use of any type of anchor in seismic conditions needs to be supported by adequate experimental evidence.

Experimental investigation of self-cleaning behaviour of 3D-printed textile fabrics with various printing parameters

Self-cleaning of textile fabrics is defined as the ability that the pollutants particles can be removed from the fabric surface without any external source. The application of the technology is beneficial to the environment since it conserves water, energy and laundry costs. In the past, it is typically obtained by chemical coatings, which develop low surface energy and high roughness on the fabric surface, allowing the pollutant particles or droplets to float over the surface rather than adhesion. These chemical coating methods are effective for fabrics manufactured by traditional woven-based textile technology. However, the recent advancements in 3D printing technology have evolved the manufacturing of textile fabrics but with equal challenges in self-cleaning as previous chemical coating-based methods are not useful for printed fabrics. A recent study has successfully established a linear regression model to demonstrate the relationship between secondary 3D printing parameters and the self-cleaning properties of different polymeric fabrics. This paper is intended to analyse the impact of the primary printing parameters on the self-cleaning attributes, including infill rate (IR), flow rate (FR), printing temperature (PT), printing speed (PS), and printing acceleration (PA). The experimental results were used to construct a regression polynomial to quantify the self-cleaning behaviour of the selected thermoplastic polyurethane (TPU) fabric. The models were validated experimentally to highlight the critical values of considered primary parameters for optimal self-cleaning behaviour. The obtained results indicated that FR was the most significant parameter, and all parameters affected the fabric's wettability almost equally.

Gas permeation and selectivity of polysulfone/carbon non-woven fabric membranes with sponge and finger-like structures

This research aims to investigate the effect of supporting polysulfone (PSF) membranes with different pore structures (sponge “SP” and finger “FP”) by non-woven carbon fibers (CF) on their gas permeability and selectivity for different gas mixtures (H2/CO2, H2/N2, and H2/CH4) to avoid the lower mechanical strength of the commercial membranes. The thickness of the PSF layer was modified during the preparation process using a phase inversion approach. The impact of the support CF fabric and different pore structures on the mechanical, chemical, thermal, permeability, and selectivity characteristics of the fabricated membranes were examined. The results revealed a strong incorporation between PSF and the fabric, resulting in enhanced pores, increased porosity and higher roughness. The FP membrane’s structure was found to have a smaller pore size of 56 nm, higher porosity (73.6%), surface roughness (44 nm) and higher strength (15.7 MPa) but less thermal stability (−36%) compared to the SP structure. Moreover, the SP structure exhibited higher gas permeability, particularly for H2, with improvements of 32% for H2 and CO2, 25% for CH4, and 10% for N2. Furthermore, the PSF/CF membrane with SP structure exhibited higher selectively with 15.8%, 26.9%, and 14.4% improvements for H2/CO2, H2/N2, H2/CH4, respectively, compared to FP membranes. These results suggest that CF fabric has great potential as a membrane substrate and PSF/CF membranes with SP structures have high potential for use in the H2 gas separation process in harsh environments.

Experimental investigation on surface topography in submerged abrasive waterjet cutting of Ti6Al4V

Some of the key issues with AWJ technology are high roughness, low depth of smooth zone, and grit embedment. When compared to the unsubmerged AWJ, the submerged AWJ gives less divergence and produces higher energy at the cross section of the jet. Hence, this study examined the effects of pressure, traverse rate, and standoff distance on roughness, depth of smooth zone, and grit embedment in both AWJ conditions. Here, single factor experiments are conducted for experimental investigation wherein one factor is varied and the others are kept constant. In comparison, the submerged AWJ gave significant improvement in the roughness and depth of the smooth zone at lower levels of pressure (150 and 200 MPa), higher levels of traverse rate (300 and 350 mm/min) and standoff distance (4, 5 and 6 mm). The significant difference in grit embedment was observed at lower levels of traverse rate (150 and 200 mm/min), higher levels of pressure (300 and 350 MPa), and all the levels of standoff distance (2, 3, 4, 5, and 6 mm). The grit embedment in the submerged condition was lower due to the removal of initially embedded grits due to flushing action produced by cavitation initiation.

A novel miniaturized pH potentiometric electrode based on a nano bismuth oxide film deposited on a fluorine doped nano tin oxide glass substrate

A novel thin film of bismuth oxide (Bi2O3) deposited on a fluorine doped tin oxide glass substrate (FTO), using a spray pyrolysis technique, was prepared and used as a pH sensing membrane. The deposited Bi2O3 film was characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM). Film prepared by pyrolysis at 550 °C displayed a tetragonal β-phase of Bi2O3 with a porous structure, high roughness surface and nano cracks. The fabricated Bi2O3/FTO film was used as a miniaturized potentiometric electrode for monitoring a wide range of pH (pH 2 – 12) in aqueous solutions. The electrode exhibited an ideal near-Nernstian response (slope of −60.2 ± 0.3 mV/decade), high potential stability, mechanical durability and good selectivity toward some common interfering cations and anions, supporting its applicability for quality control/quality assurance purposes. The performance characteristics of the electrode and validation measurements, according to the standard methods, were evaluated. The Bi2O3/FTO-based electrode was satisfactorily used for monitoring the pH of some real water, beverages and fruit juice samples and the results compared fairly well with data obtained by the conventional pH glass electrode.

Biofunctionalization of Porous Titanium Oxide through Amino Acid Coupling for Biomaterial Design.

Porous transition metal oxides are widely studied as biocompatible materials for the development of prosthetic implants. Resurfacing the oxide to improve the antibacterial properties of the material is still an open issue, as infections remain a major cause of implant failure. We investigated the functionalization of porous titanium oxide obtained by anodic oxidation with amino acids (Leucine) as a first step to couple antimicrobial peptides to the oxide surface. We adopted a two-step molecular deposition process as follows: self-assembly of aminophosphonates to titanium oxide followed by covalent coupling of Fmoc-Leucine to aminophosphonates. Molecular deposition was investigated step-by-step by Atomic Force Microscopy (AFM) and X-ray Photoemission Spectroscopy (XPS). Since the inherent high roughness of porous titanium hampers the analysis of molecular orientation on the surface, we resorted to parallel experiments on flat titanium oxide thin films. AFM nanoshaving experiments on aminophosphonates deposited on flat TiO2 indicate the formation of an aminophosphonate monolayer while angle-resolved XPS analysis gives evidence of the formation of an oriented monolayer exposing the amine groups. The availability of the amine groups at the outer interface of the monolayer was confirmed on both flat and porous substrates by the following successful coupling with Fmoc-Leucine, as indicated by high-resolution XPS analysis.

Study on particle plugging in propagating fractures based on CFD-DEM

In the drilling and completion process of fractured formations, wellbore stability is a key factor affecting the safety of drilling and completing engineering. Previous studies have demonstrated that propping moderately and plugging fractures with soluble particles can improve formation fracture pressure. When it comes to particle transport in 3D rough propagation fractures, the interactions between particle-fracture-fluid need to be considered. Meanwhile, size-exclusion, particle bridging/strain effects all influence particle transport behavior and ultimately particle plugging effectiveness. However, adequate literature review shows that fracture plugging, and fracture propagation have not been considered together. In this study, a coupled CFD-DEM method was put forward to simulate the particle plugging process of propagating fracture, and the effects of positive pressure difference, fracture roughness, particle concentration, and particle shape on the plugging mechanism were examined. It is concluded through the study that: 1) Positive pressure difference too large will lead to excessive fracture aperture, making the particles unable to form effective plugging in the middle of the fracture; positive pressure difference too small will lead to fracture aperture too small, making particles unable to enter into and plug the fracture. 2) No matter how the concentration, particle size and friction coefficient change, they mainly affect the thickness of the plugging layer, while the front end of the particle is still dominated by single-particle bridging, and double-particles bridging and multiple-particles bridging are hardly ever seen. For the wellbore strengthening approaches, such as stress cages, fracture tip sealing, etc., specific analysis should be carried out according to the occurrence of extended fractures. For example, for fractures with low roughness, the particles rarely form effective tight plugging in the middle of the fracture, so it is more suitable for fracture tip sealing; For the fracture with high roughness, if the positive pressure difference is controlled properly to ensure reasonable fracture extension, the particle plugging effect will be good, and the stress cage method is recommended for borehole strengthening.

Evaluation of adhesion strength, corrosion, and biological properties of the MWCNT/TiO2 coating intended for medical applications.

Multi-wall carbon nanotube (MWCNT) coatings are gaining increasing interest because of their special properties used in many science fields. The titania coatings are known for their improvement of osteoblast adhesion, thus changing the surface architecture. Bi-layer coatings comprising 0.25 wt% of the MWCNTs and 0.30 wt% of titania (anatase structure) were synthesized in a two-stage procedure using the electrophoretic deposition method (EPD). The MWCNT and TiO2 coatings were deposited with voltage and time parameters, respectively, of 20 V and 0.5 min, and 50 V and 4 min. EDS, AFM, SEM, Raman spectroscopy, nano-scratch test, potentiodynamic corrosion tests, wettability studies, and cytotoxicity determined with MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test on human dermal fibroblasts (HDF) and mouse osteoblast precursors (MC3T3), and lactate dehydrogenase (LDH) activity test were carried out on examined surfaces. The prepared MWCNT/TiO2 coating is uniformly distributed by MWCNTs and agglomerated by TiO2 particles of size ranging from 0.1 to 3 μm. Raman spectroscopy confirmed the anatase structure of the TiO2 addition and showed typical peaks of the MWCNTs. The MWCNT/TiO2 coating had higher roughness, higher adhesion strength, and improved corrosion resistance compared to the MWCNT basic coating. The results of biological tests proved that physicochemical properties of the surface, such as high porosity and wettability of MWCNT/TiO2-coated material, would support cell adhesion, but toxic species could be released to the culture medium, thus resulting in a decrease in proliferation.

Influence of particle size distribution on surface roughness in powder bed fusion - A contribution to increase resource efficiency

High roughness, especially on downskin surfaces, limits the high potential of powder bed-based additive manufacturing. Additionally, resource efficiency is low due to necessary powder preparation by sieving and sifting. In this examination, the potential of high output powder (maraging tool steel 1.2709), which was only marginally prepared after atomizing, was analysed in terms of roughness at different surface orientations on both the upskin and the downskin surface. The high output powder was compared to both, a powder with increased fineness and a commercially available powder, showing great potential regarding resource efficiency and roughness, especially for internal channels.

INFLUENCE OF Au3+ SWIFT HEAVY ION ON DIELECTRIC, FLUORESCENCE, SCANNING ELECTRON MICROSCOPE, AND NONLINEAR OPTICS: 2-AMINO-5-NITROPYRIDINIUM CHLORIDE (2A5NPCl) SINGLE CRYSTAL

The single crystal of 2-amino-5-nitropyridinium chloride (2A5NPCl) was developed using the assembled temperature reduction (ATR) technique and a slow evaporation solution. The crystal was cut for irradiation as it was growing. Cesium sputtering was used to choose a swift heavy ion (SHI) of Au3+ from a source of negative ions (SNICS). Au3+ ions of (1013, 5 x1013, and 1014 ions/cm2 ) different fluence irradiated on the semi-organic samples. A luminescence study reveals that intensity decreased due to the loss of luminescence property of the material, which is caused by swift heavy ions (SHI). The formation of intermediate energy levels which converted the photon into phonon affected the radiative transition. Hence, the peak shifted and the intensity of the peak decreased. More ions were activated with lattice disorders at higher fluences, which boosted the activation of ion interactions. Capacitance increased due to this interaction of ions hence dielectric constant increased as increased the ion fluence 1013 ions/cm2 through 1014 ions/cm2 . When a semi-organic 2-amino-5-nitropyridinium chloride (2A5NPCl) was exposed to high fluence radiation, pores, cracks, and roughness could all be clearly visible in the SEM along with the material's roughness. SHI significantly changed the surface of 2-amino-5-nitropyridinium chloride (2A5NPCl) at higher fluence. When compared to pristine, it was determined that the non-centro symmetric system in 2-amino-5- nitropyridinium chloride (2A5NPCl) was less impacted than in the other derivatives of the 2-amino-5- nitropyridinium families of crystals. Irradiated crystals' nonlinear optical properties were less than pristine; however, they were still higher than reference material KDP.

Physical properties and microstructure of traditional kaolin-based ceramics with additive fly–ash (FA)

In this research, the kaolin–based ceramic with 10-50 wt.% FA additive was fabricated by solid-state reaction. All powders were weighed, mixed and further milled by ball-milling for 4 h. All compositions of powders were uniaxial pressed in pellets and sintered at 1100 °C for 4 h. The XRD pattern of kaolin with FA additive showed that the kaolin phase was decreased with increasing FA and the single peak and the right shift resulted from the mix phase between quart phase and mullite phase of 40 to 50 wt.% FA. The SEM image of 10 to 30 wt.% FA addition illustrated melting grain and high roughness surface area. However, at the concentration of 40 to 50 wt.% FA addition provided the flat surface area and increased a porosity of the ceramics. The optimization of physical properties of ceramics included density, average linear shrinkage and hardness are 2.63 g/cm3, 24.62% and 135.32 kgf, respectively. The physical properties and microstructure of kaolin-based ceramics with FA additive are as the results of a structure properties relation.

Energy consumption and surface roughness maps for low and moderate speed machining of Aluminum alloy 2014: An experimental study

<abstract> <p>The rising energy prices and soaring environmental concerns have put an immense pressure on the wide usage of machining processes. The total power consumption during machining includes the power consumed by the machine itself and the power used to remove the material from the workpiece. An accurate prediction of energy consumption during the machining process is the basis for energy reduction. In this study, the specific cutting energy and surface finish for low and moderate-speed orthogonal machining of the aluminum alloy 2014 are evaluated. The measured values for the specific cutting energy and surface roughness are presented as maps on a grid, which is based on the machining parameters including the following: (1) cutting speed and (2) undeformed chip thickness. The specific cutting energy map depicts low energy consumption values of 0.52 J/mm<sup>3</sup> for the aluminum alloy 2014 at medium speed machining. The roughness maps depict high roughness values at high cutting speeds. Both maps help in optimizing the machining process to achieve a required surface roughness with minimal energy consumption. A review of a specific cutting energy map demonstrates that energy consumption decreases by increasing the cutting speeds. The decrease in energy consumption at moderate speeds corresponds to the low cutting forces. This potentially happens as a result of thermal softening of the material caused by adiabatic heating. This subsequently leads to an increase in the machinability of the aluminum alloy 2014 at moderate cutting speeds. Furthermore, the decreasing chip thickness and increasing shear angle as a result of increasing the cutting speed confirms the increased machinability of the workpiece at moderate speeds.</p> </abstract>