Surface Roughness Of Substrate Research Articles

A review on optimum substrate surface roughness to create better wetting

Surface roughness or texture is one of the key parameters for liquid fluids or liquid metals to achieve good or poor wetting. In certain applications surface roughness of a smooth surface [mirror finish] is treated as a slippery surface for poor wettability however in a few applications’ roughness surfaces are considered as better wetting, especially for liquid metals. In this regard, to understand the parameters for the optimum surface roughness of the substrates to achieve good wetting is essential. In the present review paper, an attempt has been made to find the ideal roughness value of the substrate for better wetting of liquid metals or alloys based on substrates and fluids.

Impacts of interfacial bonding between concrete substrate and cast/sprayed HPFRCC on flexural behaviour

The performance of repair materials is greatly enhanced by the integrity of the rehabilitation system, which depends on the behaviour of the boundary or interface bond between the repair material and the concrete substrate. The effects of the implementation of repair materials (casting or spraying), the spraying direction and the roughness of the concrete substrate on the interfacial bond behaviour were experimentally investigated through four-point bending tests on prisms of size 300 × 76.2 × 40 mm. As a first step, 2 cm thick concrete substrates were fabricated with five different types of surface roughness. After 28 days of curing, the repair material (a high-performance (high-ductility) fibre-reinforced cementitious composite (HPFRCC)) was sprayed or poured into specific moulds. The HPFRCC was developed using local materials and had a tensile strain capacity of 3.7%. The spraying direction and surface roughness of the concrete substrate were found to impact the ultimate deflection rate significantly; upward spraying produced the lowest deflection rate and downward spraying the highest. Because beams are often repaired from the lower part and spraying is in the upwards direction, the casting method must be used because of the negative effect of gravity on the interfacial bonding between the concrete substrate and the repair material.

Improvement of Methods and Devices for Multi-Parameter High-Voltage Testing of Dielectric Coatings

Currently, the high voltage testing method is widely used to detect pinholes and porosity defects in dielectric coatings. However, most modern coatings also have requirements for the minimum allowable coating thickness. Conducting tolerance tests on the thickness of dielectric coatings concurrently along with monitoring integrity within a single technological process appears promising. Additionally, mitigating the impact of various interfering parameters is crucial. This paper conducts a theoretical and experimental examination of spark formation processes in both gas and dielectrics. This analysis takes place during the identification of both through and non-through defects in dielectric coatings on conductive substrates. The principles of selecting the test voltage for the investigated dielectric coatings, considering the need to detect both through defects and inadmissible thinning, are theoretically and experimentally justified. It is suggested to utilize a probabilistic approach for evaluating the detectability of the mentioned defects. It is demonstrated that, when the dielectric strength of the coating is known, it is feasible to identify both through and non-through defects in coatings with a calculated probability under a specified test voltage. The conditions of occurrence of partial discharges in the process of testing are investigated, and measures to suppress their influence on the inspection results are proposed. The influence of the substrate surface roughness on the magnitude of the breakdown voltage during testing is considered.

Build Plate Roughness Study on Part Bonding for the Laser Powder Bed Fusion Process

AbstractAdditive manufacturing (AM) processes have emerged as valuable partners in conventional manufacturing, facilitating the production of low-batch components with complex geometries across diverse industries. However, despite ongoing advancements in various AM technologies, consistently achieving reliable and defect-free components remains a challenge. In powder metal AM, the use of substrates or build plates to support the entire build plays a crucial role in ensuring build stability. Build plate preparation typically involves surface grinding followed by finishing sanding, leading to variations in surface roughness between different manufacturing runs. This study aimed to elucidate the bonding characteristics at the build plate-part interface by investigating the porosity and build plate-part strength at different substrate surface roughness. To this end, a multi-roughness build plate was designed and fabricated for tensile testing via laser powder bed fusion (LPBF) processing of upright specimens. The specimens were subjected to computed tomography (CT) scans for porosity assessment, followed by tensile tests to evaluate the mechanical performance at the build plate-part interface (bp-p). CT inspection revealed no porosity at the interface for any roughness level. Furthermore, analysis of the tensile behavior in relation to substrate roughness (Ra values of 0.8 μm, 1.4 μm, 3.5 μm, and 4.4 μm) did not reveal statistically significant differences.

Study on interface adhesion between EP/IFR/HBPSi epoxy intumescent coating and steel substrate

Interface adhesion is a key factor to systematically understand heat transfer process from intumescent coating to underlying steel substrate. In this paper, epoxy intumescent coating EP/IFR/HBPSi was prepared by adding ammonium polyphosphate (APP), melamine (MEL) and a new organosilicone flame retardant phenyl silicone resin (HBPSi) to epoxy resin (EP). The temperature function was obtained by fitting the interval distance between the intumescent coating and the steel substrate measured from 23 °C to 715 °C with muffle furnace, which showed that the interface adhesion was greatly affected by the heating conditions. At the same time, the effects of incident heat flux, chemical formulation, thicknesses of epoxy intumescent coating, the composition, thickness and surface roughness of steel substrate on interface adhesion were investigated by SEM, energy spectrum analyzer, and temperature distribution measurement and so on. The results indicate that all of these factors have influence on interface adhesion. This work helps to further understand thermal protection mechanism of the intumescent coating for steel structure buildings.

Overprinting of TPU onto PA6 Substrates: The Influences of the Interfacial Area, Surface Roughness and Processing Parameters on the Adhesion between Components.

The hybridisation of injection moulding (IM) and additive manufacturing (AM) offers the opportunity to combine the high productivity of IM and the high flexibility of AM into a single process. IM parts can be overprinted through fused filament fabrication (FFF) to allow for the customisation of parts or to add new functionalities. However, the right material pair must be chosen, and processing parameters must be optimised to achieve suitable adhesion between the components. The present study dealt with the investigation of the influence of the interfacial area, substrate surface roughness and overprinting processing parameters on the adhesion between the polyamide 6 (PA6) substrate and thermoplastic polyurethane (TPU) rib overprinted via FFF. PA6 substrates were produced through the IM of plates into a mould with different textures to obtain substrates with three different surface roughnesses. The ribs with varied interfacial areas were overprinted onto produced substrates using a desktop FFF 3D printer. To study the effect of overprinting processing parameters, the ribs were overprinted under varying printing and substrate temperatures and printing speeds according to the Box-Behnken design of experiments (DoE). The chemical composition and thermal properties of used materials were determined via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The surface properties of prepared substrates were studied via digital optical microscopy (OM), through surface roughness measurements using a confocal microscope, through contact angle (CA) measurements and through the determination of free surface energy (SFE). The adhesion between the components was determined by evaluating the tear-off strength using a universal testing machine (UTM). With an increasing interfacial area, the tear-off strength decreased, while substrate surface roughness had no statistically significant effect. Overprinting parameters influenced the tear-off strength in the order of printing speed > printing temperature > substrate temperature. High values of tear-off strength were found for the lowest printing speed, while there were no important differences found between the middle and upper values. With increasing printing and substrate temperatures, the tear-off strength increased linearly. The highest value of tear-off strength (0.84 MPa) was observed at a printing temperature, substrate temperature and printing speed of 250 °C, 80 °C and 2 mm/s, respectively.

Wetting of laser-textured tungsten substrate by molten tin

In the new generation of nuclear reactors, plasma facing components tend to be designed as Sn/W composite components. Considering the combination of tin and tungsten, the wettability evaluation of Sn/W system and its influencing factors are urgent work. Wetting experiments of Sn/W system were carried out in high vacuum by using modified sessile drop method. The results show that after vacuum annealing at 1100℃, good wettability (∼ 48° intrinsic contact angle) can be obtained quickly at 900℃ below the critical temperature of 1050℃. After laser surface texturing, the greater the roughness of the tungsten substrate surface, the better the wettability can be obtained. In essence, this correspondence is closely related to the geometric parameters of the grooves formed by laser etching, which corresponds to the predicted results in Wenzel model. The phenomenon of pinning and depinning of triple lines in the later stage of spreading is related to the spreading of liquid in the groove, and the spreading rate of the latter is faster than that of macro triple line, which leads to this phenomenon.

A review on optimum substrate surface roughness to create better wetting

Surface roughness or texture is one of the key parameters for liquid fluids or the liquid metals to achieve good or poor wetting. In certain applications surface roughness of smooth surface [mirror finish] is treated as slippery surface for poor wettability however in few applications’ roughness surfaces is considered as better wetting especially for liquid metals. In this regard, to understand the optimum surface roughness of the substrates to achieve good wetting is essential. In the present review paper, an attempt has been made to find the better roughness value of the substrate for better wetting of liquid metals or alloys based on substrates and fluids.

Experimental study of the effect of target composition and heat treatment on the Ag deposit on the adhesion of the surfaces used in microelectromechanical systems (MEMS)

Adhesion force is one of the major factors in MEMS technology specifically during micro assembling via micro grippers. Regarding the light weight of MEMS devices, the contact force between MEMS devices and the microgripper surface causes distinct problems such as sticking the MEMS surface to the microgripper, so the assemble procedure can be affected and microparts not be placed in the right position. so decreasing adhesion force has a significant role in improving micron assembly. Accordingly, in the current research work, the effects of various coating materials, deposition, and annealing temperatures on the surface roughness of microgripper substrate and its morphology are experimentally investigated considering the DC sputtering magnetron method to decrease adhesion force between microgripper substrate and MEMS device. For this purpose, seventeen silicon surfaces were used of which sixteen of them coated and one is non-coated. Deposited substrates can be classified into four groups four of them are deposited with double layers using two kinds of coating materials including Ti/Ag, SiO2/Ag, Ti/Ag-Pd-Cu, and SiO2/Ag-Pd-Cu respectively. After sample deposition, the AFM method was used to measure, the topographic images, the surface roughness, and the adhesion force. Regarding the differences in layers and distinct temperatures, the height and shape of hillocks directly depend on deposition and preheating temperature ranges. So as the deposition and preheating temperature increase, more hillocks grow and the adhesion force is more consequently. to 373 K and 573 K. Additionally, these changes result in changes in adhesion force.

The impact of hBN layers on guided exciton–polariton modes in WS2 multilayers

Abstract Guided exciton–polariton modes naturally exist in bare transition metal dichalcogenide (TMDC) layers due to self-hybridization between excitons and photons. However, these guided polariton modes exhibit a limited propagation distance owing to the substantial exciton absorption within the material. Here, we investigated the impact of hexagonal boron nitride (hBN) layers on guided exciton–polariton modes in WS2 multilayers. By integrating hBN layers, we demonstrate a notable enhancement in the quality of guided exciton–polariton modes. The hBN layers can reduce substrate surface roughness and provide surface protection for the WS2 layer, mitigating inhomogeneous broadening of the exciton resonance. Consequently, we experimentally observed that the propagation distance of polariton modes substantially increased with hBN layers. Additionally, the polariton spectrum broadened due to efficient exciton relaxation to the polariton states at lower energies. Comparison with simulation data emphasizes that the observed improvements are primarily attributed to enhanced exciton quality. The promising outcomes with hBN encapsulation suggest its potential to overcome strong excitonic losses of the guided exciton polariton in implementing nanophotonic devices. Furthermore, this approach provides a new avenue for exploring the novel physics of guided exciton–polariton modes and their potential applications in polariton-based all-optical integrated circuits.

Electrochemical performance of metal nitride coated titanium bipolar plate for proton exchange membrane water electrolyser

In order to improve corrosion resistance and electric conductivity of titanium bipolar plate (BPP) for proton exchange membrane water electrolyser (PEMWE), three different metal nitride (i.e.Ta/TaN, Cr/CrN and Nb/NbN) coated titanium bipolar plates are prepared by magnetron sputtering. The coated BPP is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscope (AFM), and their electrochemical performance is assessed by electrochemical corrosion tests including open circuit voltage (OCP), potentiodynamic and potentiostatic polarization tests in the simulated PEMWE anode environment. It is revealed that the surface roughness of titanium substrates is decreased after coating, implicating the reduced interfacial contact resistance (ICR). Potentiodynamic and potentiostatic tests demonstrate that Ta/TaN and Nb/NbN coatings can significantly improve the corrosion resistance of titanium bipolar plate. The corrosion current density of coated substrate is reduced by approximately 67 % upon coating with Ta/TaN and Nb/NbN under the simulated PEMWE anode environment. However, the ICR of Ta/TaN coating is the lowest (3.9 mΩ × cm2), which is reduced by 74 % compared with pristine titanium substrate (14.9 mΩ × cm2). Hence, the Ta/TaN coated BPP is tested in single electrolytic cell and demonstrates significantly improved electrolysis efficiency.

Influence of substrate surface roughness on the thermal emissivity of titanium carbide coatings on graphite

This study focused on the impact of substrates shape on the heat radiationcharacteristics of a coating made of titanium carbide, TiC, deposited over a graphite basis. The TiC coating emissivity increase by 29.65% at 1050?C and by 37.45% at 1650?C when graphite, substrate surface roughness, was decreased from 3.01 ?m to 0.73 ?m. Simultaneously, the TiC coating?s spectrum emissivity on the graphite substrate indicated the material?s clear characteristic heat radiation. These findings demonstrated that the coating and substrate interacted to determine the coating?s heat radiation properties. A simplified coating model created to consider how the shape of the substrate affects the coating?s ability to conduct heat. Ultimately, the rough form of the substrate led to a decrease in the coating?s heat radiation characteristics and an enhancement in energy loss at the interface.

Effect of curing conditions and formulation on the adhesive strength of stone-siporex mortar composite

Background: Adhesive strength is one of the most important properties of the hardened mortar, and influenced by mortar workability (i.e. mortar water content), and substrate roughness surface degree. Objective: This study aims to measure the adhesion strength between three different hydrated aerial lime mortars, and the two most common building units in old and modern building in Loire valley in France: Tuffeau and Siporex, under different relative humidity (12,66,98%) and curing periods (7,28,90 days). Materials and Methods: These mortars include: B/F (1:5.6: Moisture=46 %, aggregate stone powder pass sieve NO.2mm), B/W (1:5.6: Moisture=44 %, aggregate stone powder pass sieveNO.2mm and retained on sieve NO. 0.16mm), and B/F/M (1:5.6: Moisture=35%: superplasticizer water reducer Melment F10 (2.5% of lime amount), aggregate stone powder pass sieve NO.2mm). Numerous complementary techniques have been used to achieve this study, such as: x-ray diffraction, coupled plasma optical emission spectrometry, mercury intrusion porosimetry, mortars axial expansion by consolidation apparatus, and Proceq-DY-215 apparatus for adhesive strength measurement. Results: The results showed that expansion of B/F, B/W, and B/F/M has little effect on their adhesion strength with Tuffeau /Siporex substrates. Also, the adopted relative humidity variations had a limited effect on the adhesion strength of B/W along the curing periods (7, 28, and 90 days), with noticeable effect for the other mortars. Conclusions: The conclusions referred to the important impact of the degree of substrate surface roughness on the adhesive strength of all used mortars, where the use of Siporex as substrate recorded a clear advantage compared to Tuffeau under all used relative humidity and curing periods.

Effect of substrate roughness on the nucleation and growth behaviour of microwave plasma enhanced CVD diamond films – a case study

The influence of substrate surface roughness on the nucleation and growth of diamond films by chemical vapour deposition (CVD) is investigated. Silicon substrates were grinded with six different grit sizes of abrasive papers with a rotating wheel. Si was also etched by Ar+ ions to produce average surface roughness Ra = 11.29 nm on the mirror polished side (Ra = 1.17 nm). A comparison of the results of the effect of substrate roughness, on the growth behaviour of nanocrystalline diamond (NCD) films, by using both the resonant cavity and the linear antenna CVD systems, are presented here. Scanning electron microscopy (SEM) images and Raman spectroscopy reveal that under both the linear antenna and the resonant cavity microwave plasma CVD conditions, grown films are NCD. The diamond nanocrystals sizes vary from 80 to 180 nm, grown by both the reactors after few hours of deposition, irrespective of the substrate roughness, whereas their quality (defined by the relative percentage ratios of the Raman sp3 peak intensity to the non-sp3 peak intensity) varies from 33% to 45%, depending on the substrate surface roughness. Such nanocrystals grew into plate-like flat 1–6 μm size diamond grains after prolonged hours (64–69 h) of CVD growth. It is found specifically that the roughness created by the argon plasma treatment of the silicon substrate surfaces effectively enhances the nucleation and growth behaviour of the diamond films.

Synthesis of Aptes-Capped Self-Adsorption Pd Nanoparticles and Application in Metallization on Glass Substrate with High Adhesion

Palladium is the most used catalysts in the electroless deposition process. The technology that use the amino silane compound (3-Aminopropyl) Triethoxysilane (APTES) as surface modifier is quite mature. Therefore, an innovative idea that one step palladium catalyst APTES-Pd with APTES as capping agent and surface modifier appeared. APTES-Pd is capable to adsorb on surface of glass substrate by forming Si-O covalent bond. Comparing to commercial palladium catalysts, the process is complex and need to work at high concentration, APTES-Pd has easier process and able to work at low concentration. The particle size of APTES-Pd is characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The configuration of APTES-Pd as well as the effect of modification on glass substrate is explained by X-ray photoelectron spectroscopy (XPS).Glass substrate is a good option as an interposer substrate. It has serval advantages, such as low k, high resistivity, high stability, low coefficient of thermal expansion (CTE) mismatch with copper material and good mechanical properties. However, because glass substrate (SiO2) is stable and surface is smooth, it’s hard to electroless deposit Cu layer with high adhesion on it. The adhesion that using commercial palladium catalysts Sn/Pd for electroless copper deposition is too low to pass tape test. Because interaction between Sn/Pd and substrate is electrostatic adsorption which is lower than covalent bond. Using APTES-Pd for electroless copper deposition is capable to improve the interaction between glass and Cu layer. APTES-Pd can pass tape test on glass substrate. But its adhesion is still too low to be measured by T-Peel. To enhance the adhesion of the metal films on glass substrates, we coat titanium dioxide (TiO2) as adhesion promoter. TiO2 can not only bond to glass substrate but increase surface roughness. After coating TiO2 film, the adhesion of metal film increases to 122 gf/cm.

INFLUENCE OF SUBSTRATE SURFACE ROUGHNESS ON PUSH-OFF STRENGTH FOR FRICTION SURFACING OF LOW CARBON STEEL WITH AA6061-T6 ALUMINIUM ALLOY

Surface roughness plays an essential role in friction surfacing deposition as a smooth substrate surface polishes both consumable and substrate tools, resulting in a lack of deposition. Hence, an attempt is made to investigate the effect of substrate surface roughness while friction surfacing of AA6061-T6 coating on CR01 low carbon steel and its performance is compared through push-off strength. It is revealed that with an increase in substrate surface roughness, more rubbing action occurs between consumable tool and substrate, which results in higher heat generation and reduction in deposition thickness. The grain refinement is observed at the coating region due to dynamic recrystallisation, which results in fine grain microstructure. The substrate with Ra roughness values 1.5-2.5, 5.5-6.5 and 7.5-8.5 µm showed 26, 32 and 45 MPa push-off strength, respectively. Hence, it is inferred that the push-off strength increases substantially with an increase in the substrate surface roughness.

Evaluation of peel resistance of paint coatings depending on the roughness of the cement substrate

The object of the study is paint and varnish coatings of cement concrete. The goal is to evaluate the stress-strain state of coatings under the action of temperature depending on the geometry of the substrate roughness relief. The results of calculating the distribution of stresses over the cross section of the coatings and the possibility of their peeling are presented. The SCAD Office software module was used for the calculation. Heavy concrete was considered as the substrate. Polyvinyl acetate cement PVAC paint was used as a paint composition. The calculations were carried out for the conditions of Moscow. A comparison is made of the stresses in the coating on a smooth and rough surface. I has been found that an increase in the relief angle of the substrate surface roughness does not cause a significant change in the magnitude of stresses. The stress concentration in the zone of contact between the coating and the rough surface of the cement substrate has been established. A diagram of the distribution of stresses in the PVAC coating is presented. It was revealed that at some distance from the zone of the microdepression of the substrate surface relief, an increase in stresses is observed, which, depending on the angle of inclination of the relief, are s х = (1.007-1.021) MPa. At the peak of the relief, the stress values in the contact zone are less and amount to 0.403-0.441 MPa. The influence of the substrate roughness has practically no effect on the values of normal stresses on the coating surface, which are 0.835-1.001 MPa. The probability of peeling off the coating is estimated. The possibility of peeling of the coating has been established, tk. stress values are less than the adhesion strength, which is 0.9-1.1 MPa. It is recommended that in order to increase the resistance of coatings to peeling, strive to create a uniformly distributed roughness of the substrate surface.

Interfacial mechanical properties of graphene on randomly rough PET substrate surface: A molecular dynamics study

In this work, molecular dynamics (MD) simulations are performed to create a series of polyethylene terephthalate (PET) substrates with random roughness, and the morphological characteristics and interfacial bonding of graphene on the real rough PET surface are first simulated. The results show that the interfacial mechanical behavior of graphene freely adhered to the PET roughness is influenced by the surface profile. Besides causing the non-conformal contact, the rough surface hinders the propagation of bending waves from the graphene corner regions during the adhesion and weakens their overlap. The increased surface roughness weakens interfacial adhesion and inhibits interfacial sliding, leading to the formation of larger morphological defects such as wrinkles. Furthermore, the measurement of the interfacial adhesion energy of graphene/PET substrate is achieved by the shaft loaded blister test (SLBT), which for the first time is used to simulate the interfacial debonding of graphene on rough PET surfaces. For low surface roughness, interfacial adhesion dominates the debonding behavior and the blister boundary preferentially extends along the interfacial defect area. For high surface roughness, the increasingly serious non-conformal contact makes the blister more likely to instability and enter the stage where normal and shear interactions are coupled.

Relationship between bonding strength and surface roughness in low-temperature bonding of glass for micro/nanofluidic device

The bonding of glass substrates is an important process in the fabrication of glass micro/nanofluidic devices. In this study, the influence of the surface roughness of glass substrates after low-temperature bonding is investigated. It is found that plasma etching can be used to control the surface roughness to the range 2–9 nm. Substrates with a roughness of 5 nm or less can be bonded. The pressure capacity of devices tends to decrease with increasing surface roughness. A pressure capacity of 500 kPa or higher is obtained with a surface roughness of 2 nm or less. This criterion for bonding conditions can be applied to roughness formed by other methods (e.g. via a Cr layer). The proposed approach will facilitate the design and fabrication of glass micro/nanofluidic devices, especially those that complicated fabrication processes or embedding of multiple materials.

CO2-philicity to CO2-phobicity Transition on Smooth and Stochastic Rough Cu-like Substrate Surfaces.

CO2 on metal substrates is essential to CO2 liquefaction and transportation of CO2, yet the manipulation of the wettability of the CO2 and the elucidation of its underlying mechanism have not been fully achieved. Here, using molecular dynamics simulations, we report CO2 wetting characteristics on both smooth and stochastic rough Cu-like substrate surfaces. The results indicate that the apparent contact angle (CA) of the CO2 droplet on the smooth surface decreases from 180° to 0° as the CO2-solid characteristic interaction energy increases from 0.002 to 0.016 eV. In addition, the CAs become greater with increasing the density of surface asperities, regardless of the intrinsic surface wettability. This is attributed to the capillary drying-out of liquid CO2 molecules in gaps between surface asperities at the three-phase contact line of the droplet, which is usually overlooked in previous theoretical studies. Notably, the intrinsically CO2-philic surface transforms to the CO2-phobic due to an increase in the density of surface rugosity. Moreover, we verify the range of applicability of the CA prediction models concerning the nanoscale asperities. This work is beneficial for fully understanding the influence of nanoscale surface topography on CO2 wettability and shedding light on the design of functionalized and patterned surfaces to manipulate CO2 wettability.