Substrate Surface Preparation Research Articles

Comparative studies on interfacial bond performance of ultrahigh performance concrete (UHPC) for sustainable repair of bridges and pavements

Ultra high performance concrete (UHPC) is emerging as an innovative sustainable solution to rehabilitate deteriorated concrete pavements and bridges. In such usage, UHPC may be cast against different substrate materials such as normal strength concrete (NSC) for bridge strengthening and rehabilitation or against high strength concrete (HSC) for shear key connections. UHPC may also be cast against precast UHPC due to the rapid increase in using precast UHPC components. Although the UHPC usage in above applications has recently increased, an investigation of bond performance between UHPC and three different substrate materials have not yet been investigated. The study examined the bond performance between cast-in-place UHPC and three different substrate materials. Three different surface preparations were considered in the current study: smooth, exposed aggregate/fibers and grooved. To generalize the outcomes from the present study, three different test methods including, splitting, bi-shear and slant shear with three different slants were selected. The experimental results demonstrated that the UHPC adhered better with NSC and HSC substrates when the pressure washing was used to expose the aggregate. Meanwhile, the UHPC had better bond with grooved surface preparation of UHPC substrate. The smooth surface should be avoided when UHPC cast against all substrates. Furthermore, the friction coefficients from the codes were overestimated for smooth surface regardless the substrate strengths. However, the design codes provided a conservative estimate for both cohesion and friction coefficients for exposed aggregate/fibers and grooved interface surface preparations.

Application of Organo-Modified Silica Nanoparticles to Improve the Load-Bearing Capacity of Bonded Joints of Dissimilar Steel Substrates

The paper deals with the joining of dissimilar steels by adhesive bonding. The base materials for the experimental work were deep-drawn low-carbon steel DC04, and hot-dip galvanized HSLA steel HX340LAD+Z. Adhesive bonding was performed using rubber-based and epoxy-based adhesives. The research aimed to verify the importance of surface preparation of steel substrates using a formulation with organically modified silica nanoparticles and epoxy organic functional groups, where one end of the functional group can be incorporated into the organic binder of the coating material and the other end can be firmly bonded to substances of an inorganic nature (metals). Since the binder base of adhesives is very similar to that of coatings, verifying the performance of this surface preparation when interacting with the adhesive is necessary. The load-bearing tensile shear capacity of single-lapped joints and the resistance of the joints against corrosion-induced disbanding in a climate chamber were tested. The energy dissipated by the joints up to fracture was calculated from the load-displacement curves. Bonded joints with organosilane were compared with joints without surface preparation and joints prepared by chroman-free zirconate passivation treatment. Exposure of the joints in the climatic chamber did not cause a relevant reduction in the characteristics of the joints. Organosilicate formulation was proved effective when bonding ungalvanized steels with a rubber-based structural adhesive, where it improves the bond quality between the adhesive and the substrate.

REVIEW: MATERIALS FOR IMPREGNATION OF POROUS METALLIZATION THERMAL SPRAYED ANTICORROSIVE COATINGS OF SUBMERSIBLEOILFIELD EQUIPMENT. Part 1

Submersible oilfield equipment undergoes aggressive corrosive effects of petroleum fluid, abrasive effects of mechanical impurities during operation, and also operates at elevated temperatures in the bottom. The most effective way to protect the outer surface of oilfield equipment is the use of metallization thermal sprayed coatings, and therefore the application of thermal spraying technology is becoming more and more in demand.However, the formation of a coating structure from many particles of molten material, due to their spraying, incomplete melting and loose packaging, leads to the formation of porosity, and porosity is one of the main disadvantages of thermal sprayed coatings. To eliminate this disadvantage, it is possible to use impregnation of porous coatings with various compositions, in which case the coating becomes composite. Depending on the operating environment, temperature conditions and operating conditions, metal, organic and inorganic impregnating compositions are used,but their use in the oil environment has been little studied, therefore the development of composite impregnated coatings is relevant for the protection of submersible oilfield equipment. The article highlights the influence of technological modes of its application on the porosity of thermal sprayed coating and the quality of substrate surface preparation. The main methods of sealing the porosity of thermal sprayed coatings by impregnation are described. The mechanism of impregnation (infiltration) of porous coatings, used methods of application and their classification are described, the determining role of wetting the coating with an impregnating material is emphasized. The effect of the rough surface of a thermal sprayed coating is shown, which consists in enhancing the wetting properties of the impregnating composition, the influence of roughness on the formation of adhesive bonds between the coating and the impregnating composition.The review presents traditional impregnating materials used in industry and their application modes.The application of metal and non-polymer inorganic impregnating compounds, represented mainly by salts of inorganic acids (nitrates, phosphates, silicates), is described. Specific test results are presented, including for the corrosion and abrasive resistance of thermal sprayed coatings after the application of impregnating compounds.

Construction Methods and Lessons Learned for a Non-Proprietary Ultra-High Performance Concrete Overlay

The work presented in this paper includes the construction methods and lessons learned from the placement of a non-proprietary ultra-high performance concrete (UHPC) overlay through the rehabilitation of a concrete bridge deck located in Socorro, New Mexico, USA. The selected bridge is a multi-cell, box girder bridge with four spans and a total length of 91.4 m and a width of 16.5 m with two traffic lanes. Rehabilitation of the bridge involved removing the top surface of the existing deck (deteriorated concrete), installing a high-performance deck (HPD) leveling course, and placing a 25 mm UHPC overlay. Sensors were installed in the bridge superstructure (multi-cell box girders, HPD, and overlay) for long-term monitoring. Overlay assessment included physical testing to evaluate the condition of the overlay–substrate bond by chain dragging and direct tension pull-off testing. Conclusions and lessons learned from this investigation serve as a fundamental list of best practices and recommendations for field construction of a non-proprietary UHPC overlay. Recommendations for preparatory tasks including material selection, substrate surface preparation, placement preparation, handling of materials, and UHPC mixing are provided. The recommendations also list best practices concerning the placement of the overlay, curing procedures, and quality assurance testing. Lastly, suggestions are presented for contracts pertaining to UHPC overlay projects.

Influence of the EPD route and surface preparation of titanium substrates on the microstructure, surface topography and usage properties of chitosan coatings incorporated in Tea Tree Oil and Terpinen-4-ol

The electrophoretic deposition (EPD) of Tea Tree Oil (TTO)/chitosan and Terpinen-4-ol/chitosan coatings on titanium substrates with different surface preparations was examined. The deposition was performed with vertical and horizontal configurations of electrodes, called horizontal and vertical EPD, respectively, following the direction of the electric field. The data obtained showed the influence of both the electrode configuration and substrate surface preparation on the EPD process as well as coating properties, such as adhesion, morphology, microstructure, roughness, surface topography and wettability. The most promising coatings were obtained for vertical EPD and ground titanium substrates. They were relatively homogeneous and consisted of droplets of TTO or Terpinen-4-ol embedded in chitosan. The formation of hydrogen bonds between chitosan chains and Terpinen-4-ol was detected and the responsible mechanism was indicated. The coatings exhibited high adhesion strength, relatively low wettability as well as medium roughness. Both coatings improved the corrosion resistance of the titanium in Hanks’ solution. This work showed that natural chitosan-based coatings incorporated in TTO and Terpinen-4-ol are promising for the antimicrobial protection of titanium. Terpinen-4-ol/chitosan surfaces has shown favorable antibacterial properties, but it is interesting that it can be combined with chitosan to further increase this potential, besides, they had the highest biocompatibility.

Achieving Metallurgical Bonding in Aluminum/Steel Bimetallic Castings

Aluminum castings are increasingly being used in automotive powertrain and structural applications for vehicle lightweighting. Cast aluminum parts often need to be machined and joined to steel components in multi-material systems. Bimetallic components produced by casting aluminum over steel substrate are advantageous due to the elimination of machining and traditional dissimilar material joining processes. However, forming a strong metallurgical bonding during overcasting process has been challenging. In this paper, the effects of processing conditions such as substrate surface preparation, pre-heating temperature, melt conditions as well as casting design were studied by investigating the bimetallic interfaces for aluminum A319 casting alloy and a high alloy steel substrate in a sand-casting process. Zn and Al-based substrate coatings were evaluated. The experimental results suggest a metallurgical bond between aluminum and steel can be formed during the sand-casting process via high temperature diffusion with or without coatings. Al-based substrate coating prior to overcasting results in the formation of a continuous layer of intermetallics at the bimetallic interface, with large Al–Si–Fe intermetallics penetrating the cast aluminum.

Magnesium nanoparticle modified cement-based composites: Performance and compatibility in repair applications

Applying ordinary repair mortars onto the surface of degraded concrete elements has been a common approach in restoration operations. Since the properties of cement-based composites depend on nano-structural features, proper addition of nanoparticles can enhance performance. In the present study, the physico-mechanical performance of concrete and mortar mixtures incorporating magnesium nanoparticles was investigated. The workability and flowability of the mixtures, along with compressive, tensile, and flexural strengths of specimens were evaluated. A total of 284 cylindrical, cubic, and prismatic beam specimens having different dosages of magnesium nanoparticles as partial replacement for cement were assessed to quantify the effects of adding magnesium nanoparticles. Furthermore, analysis of the compatibility between the repair mortar and the existing concrete substrate was examined using four-point bending tests on repaired beam elements to characterize the different modes of failure. Two approaches of substrate surface preparation featuring smooth and rough interfaces were adopted, and the effect of interface texture on the mechanical properties of the repaired beam specimens was evaluated. The results show that specimens incorporating magnesium nanoparticles achieved 37%, 37%, and 63% higher compressive, tensile, and flexural strengths, respectively, compared with that of the reference specimens. Moreover, the set of concrete beams with rough interface showed compatible failure modes, while those with smooth contact interface had incompatible modes of failure.

Influence of Si surface preparation on CoSi2 formation and agglomeration

In microelectronics, despite a difficult nucleation of cobalt silicide CoSi2 in small dimensions, the CoSi2 based contacts remain interesting for some specific devices designed in 65 nm technology. Therefore, to promote the formation of CoSi2 in 65 nm technologies, it is possible to interfere on the formation of CoSi, that occurs during RTA1. To this end, the surface preparation of the Si substrate, before the Co deposition, may have an influence on the cobalt silicide phases formation. In this work, different surface preparations (SiCoNi, HF followed by SC1 and HF only), as well as several Soft Sputter Etch, SSE, processes have been applied on Si(100) wafers before the deposition of Co and TiN layers. Depending on the surface preparation, the formation temperatures and/or crystalline orientations for the Co silicide phases, including CoSi2, are different, as observed by XRD and/or EBSD. Four-point probes measurements also show a strong dependency of the CoSi2 agglomeration to the surface preparation scheme. These results highlight the influence of surface preparation on the Co silicides formation and agglomeration and its importance for the integration of CoSi2 films in a 65 nm CMOS technology.

The Technological Factors and Operating Conditions Influence on the Molybdenum Disulfide Coatings Tribological Properties

Molybdenum disulfide is a widely used solid lubricant operates successfully under extreme conditions such as vacuum, high or low temperatures, high loads etc. Magnetron sputtering is one of the most common method of application MoS2 coatings. It allows one to apply thin antifrictional films with high rate of purity on different substrates. The surface before application is usually prepared by abrasive processing. The aim of the work is to evaluate the magnetron deposition modes, substrate surface preparation, substrate roughness on the molybdenum disulfide coatings tribological properties. For the purpose mentioned a linearly reciprocating Ball-on-Flat (ASTM G133) Sliding Wear tests in vacuum (pressure less than 10-4 mbar) and high temperature (250 ¬¬¬0C) were conducted. The two different materials as a coating substrate was used (stainless steel and brass). The substrate surface was sandblasted. The coating surfaces structure after wear and chemical composition have been studied. The friction coefficient in vacuum at 250 °C was about 0.02–0.05. The least value was observed for the AISI 316L steel substrate treated by sandpaper and Ra 0.10 µm roughness coatings. The negative bias voltage (–20 V) during magnetron deposition leads to 16–42% lower coefficient of friction. Oxygen decreases the anti-friction properties.

Cryogenic ultrasonic vibration assisted turning to texturize AZ31 magnesium alloy surfaces

Magnesium alloys are increasingly used in the biomedical field thanks to their biocompatibility. However, poor corrosion resistance greatly limits their applications. Coating the devices is known to represent the most efficient way to increase the corrosion performances of magnesium alloys, but it requires specific surface preparation of the metal substrate. In the present paper, a hybrid machining technology, namely cryogenic–ultrasonic-assisted turning, is applied to generate magnesium alloy texturized surfaces with enhanced surface integrity characteristics. Results showed that the application of liquid nitrogen led to a harder and more complex surface texture than in the case of ultrasonic-assisted turning under dry conditions.

Effect of bridge deck surface preparation on the consolidation and bond of UHPC overlays

This investigation studies the effect of concrete substrate surface preparation methods on ultra-high performance concrete (UHPC) overlay bonds. Substrate surface roughnesses were analyzed using profile chips and a laser. After applying overlays to the substrates, direct tensile pull-off testing was performed to assess bond strength. Scanning electron microscopy was then used to observe representative interfaces. The study found that UHPC rheology and consolidation can significantly affect UHPC overlay bond with a high-amplitude roughness concrete substrate, particularly for thixotropic UHPCs. Surface retarder finishes were found to offer reasonably similar overlay bond performance to that of a hydromilled concrete substrate.

Hard ultralight systems by thermal spray deposition of WC-CoCr onto AZ31 magnesium alloy

Magnesium alloys in general, and AZ31 in particular, have huge potential as materials for energy saving and emissions reduction in the transportation of people and goods, because of their low density (about 1.7 g∙cm−3) coupled to good bulk mechanical properties. The main weakness is represented by the alloy surface, prone to corrosion and rather soft. Coatings are therefore mandatory, especially in harsh environments. To obtain AZ31 materials with exceptional surface properties High Velocity Oxygen-Fuel (HVOF) thermal spray was exploited to deposit a WC-CoCr coating with very high surface hardness. Because of the heat sensitivity of magnesium alloys, the influence of torch-substrate kinematics and substrate surface preparation on the surface temperature during deposition, the metallurgical characteristics of AZ31, and the residual stress state of the coated samples were investigated. The overall quality of the coatings was also evaluated by abrasion and electrochemical corrosion resistance tests. Proper adjustment of the torch/substrate standoff distance and torch patterning strategy reduced the surface temperature during deposition by around 100 °C, as measured with an IR pyrometer. This also resulted in a decreased magnitude of the average compressive stress in the coating. At the same time, these adjustments did not impair measurably the performances of the coatings, which, regardless of the deposition conditions, had approximately 1200 HV0.3 hardness, 2–4 μA∙cm−2 corrosion current density in 3.5 wt./vol% NaCl aqueous solution, and 7–8 × 10−4 mm3∙(N∙m)−1 specific wear rate under dry particles' abrasion conditions. Cyclic impact tests also showed that the coatings adhered equally well to grit-blasted or machined surfaces. On the other hand, transverse cracks developed across the coatings during impact tests because of the much higher elastic and plastic deformability of the AZ31 substrate. The avoidance of grit-blasting and the lowered deposition temperatures were also important to prevent anomalous grain growth in the AZ31 substrate.

An Investigation of Tin Electroless Deposition

Electroless metal/alloy deposition can be an efficient process in certain areas of microelectronic fabrication. In fact, it is often easier to obtain coatings of uniform thickness and composition using electroless deposition than with electrodeposition, since one does not have the current density uniformity problem of the latter. For example, we were able to develop a Ni(P) process as a replacement for the final aluminum interconnect level, significantly decreasing wafer processing cycle time, by selectively depositing a Ni(P) capping layer on the Cu bitline wiring level. In STTM MRAM, we successfully employed this Ni(P) capping process to enable the evaluation of memory state retention via functional testing in an air atmosphere at elevated temperatures (1).However, there is a need to explore materials + deposition methods for rapidly developing fields, such as Quantum computing, e.g., materials with superconducting properties. Conventional electroless metal deposition, utilizing a separate reducing agent, can deposit materials with unique and useful properties, such as phosphorus-containing alloys in the case of hypophosphite reducing agents. This talk discusses work we have carried out on electroless tin deposition, including aspects of electroless solution preparation and stability, copper substrate surface preparation and catalyzation, and the mechanisms of electroless deposition and solution decomposition.Electroless processes can deposit a limited number of materials, especially pure metals. This is in part due to conventional electroless processes requiring catalytically active surfaces both to initiate the deposition reaction and to sustain it, the heterogeneous oxidation of the reducing agent being a kinetically hindered process, often with multiple reaction pathways (2). Though not possessing good catalytic activity due to its Periodic Table related, p -block element status, pure Sn, an environmentally robust, superconducting metal, can be electrolessly deposited through a disproportionation reaction involving stannous ions (3) in an alkaline aqueous medium.We achieved electroless Sn deposition rates of up to 8 – 9 μm/hr for tartrate-citrate complexed electroless Sn solutions in the temperature range 80 – 85 ⁰C with sodium and potassium hydroxides to adjust alkalinity. We found that either in-house formulated, or commercially available, immersion Sn solutions deposited a uniform Sn catalyst layer (≤ 0.5 μm) to initiate the electroless Sn deposition reaction on copper; however, improperly formulated immersion Sn solutions rapidly developed precipitates due to tin ion hydrolysis.The biggest technical challenge was minimizing unwanted electroless deposition of tin in bulk solution, i.e., deposition not associated with the catalytically active substrate surface. Tin oxide (SnO) is known to be metastable at ambient conditions and to decompose at temperatures above 300 ⁰C with “noticeable rate” into Sn and SnO2 (4). Thus, removal of filterable hydrolysis products of Sn(II) following solution preparation was important, but not always sufficient, for obtaining solutions that were viable for several days of use. The reasons for, and mechanisms of, electroless Sn solution decomposition do not appear to have been adequately addressed in the literature.We will show SIMS analysis of both immersion and electroless Sn layers along with synchrotron X-Ray analysis results of immersion Sn catalyst films on Cu to determine the extent of Sn-Cu intermetallic formation following their formation. We will discuss the current understanding of the mechanism of electroless Sn deposition including that of concomitant H2 gas evolution. We will conclude with contrasting the Ni(P) and Sn electroless processes in terms of ease of operation and reliability for routine processing. † Present address: Solvay, 1937 West Main Street, Stamford 06902, CT. ‡ Quantum intern at the IBM TJ Watson Research Center, Summer 2019, 2020 and 2021.[1]. E. J. O'Sullivan, C. Camagong et al., 2019 Meet. Abstr. MA2019-02 916; https://doi.org/10.1149/MA2019-02/15/916.[2]. E. J. O'Sullivan, Ch 5, Advances in Electrochemical Science and Engineering, Volume 7, https://doi.org/10.1002/3527600264.ch5.[3]. A. Molenaar and J. W. G. de Bakker, 1989, J. Electrochem. Soc. 136, 378 and refs therein; H. Koyano, M. Kato, and M. Uchida, 1991, Plating and Surface Finishing, 78, 68-74 and refs therein.[4]. H. Giefers et al, 2005, Solid State Ionics, 176, 199-207; https://doi.org/10.1016/j.ssi.2004.06.006. Acknowledgements The authors gratefully acknowledge the efforts of the staff of the Microelectronics Research Laboratory (MRL) at the IBM T. J. Watson Research Center, where some of the fabrication work described in this talk was carried out.

Effect of Surface Pre-Treatment on the Adhesion between HiPIMS Thick Cu:CuCNx Coating and WC-Co Shim

High-power impulse magnetron-sputtering thick metal/carbon–nitride-doped metal-matrix multilayer nano-composite coating can be applied to cutting-tool holder components to improve cutting insert’s life. One of the challenges of such an add-on solution is the poor adhesion between the thick coating and the hard alloy substrate, such as WC-Co shim. This work presents a study on WC-Co substrate surface preparation methods for HiPIMS coating and its adhesion improvement. Three mechanical surface pretreatment methods were investigated: machining (grinding), diamond polishing, and grit blasting. White-light interferometry was used for substrate surface texture measurement before and after pretreatment. It was demonstrated that, compared to machining and diamond polishing, grit blasting can significantly improve the interface adhesion between the ~200 µm-thick Cu:CuCNx coating and WC-Co shim. Grit blasting was also found to be beneficial for improving the cutting insert’s life in the external turning process. In turning tests, the coating lifetime for grit-blasted shim was more than 90 min, whereas the coating lifetimes for machined shim (conventional shim) and diamond-polished shim were ~85 min and ~70 min, respectively. Further, by comparing the HiPIMS gradient chromium pre-layer between the coating and substrate for the different shims, the study also explained that the quasi-isotropic surface texture of grit-blasted shim is more advantageous for coating–substrate interface adhesion.

Effect of surface treatment on the performance of composite‐composite and composite‐metal adhesive joints

AbstractThe use of Fiber‐Reinforced Polymer Composites (FRPCs) in automotive, aerospace, and naval applications has increased significantly due to the requirement for a high performance‐to‐weight ratio. One the issue in using composite parts is their joining to the metal parts in the global structure. Several joining techniques such as mechanical joining, adhesive, vibration joining, and hybrid joining are used for this purpose. Being lighter in weight and lower in cost in comparison to other techniques, adhesive bonding is mostly used for composite‐composite and composite‐metal joining. To achieve reliable adhesive joining, surface preparation of the joining substrates is of utmost importance. Though the effect of physical surface treatments on the performance of joints has been reported in the literature, however, the effect of chemical surface treatment of composites on the mechanical performance of adhesive joints was rarely studied. In this article, the effect of chemical treatment (alkaline permanganate), of the composite surfaces on the single lap shear strength and Izod impact strength of composite‐composite and composite‐metal adhesive joints is reported. The results showed that the chemically treated joints demonstrate a significant improvement in these properties.

Effect of substrate surface finish and particle velocity on fatigue performance of cold spray coated A6061 aluminum alloy

Cold spray coatings made with powder of the same material as the substrate can be used to improve fatigue performance and/or to repair damaged parts. The effects of substrate surface finish and particle impact velocity on the bond strength and fatigue performance of Al-6061-T6 substrates coated with Al-6061 powder by using high pressure cold spray (CS) were investigated. To evaluate the effect of particle velocity, coatings were prepared by using both nitrogen (N2) and helium (He) as carrier gases. A new method for substrate surface preparation was introduced by low angle spraying (LAS) with the same powder prior to coating. The bond bar specimens in polished, semi-polished, grit-blasted (GB) and low angle sprayed (LAS) conditions were coated and tested for bonding strength. The microstructural characteristics and microhardness profiles of the coated samples were also evaluated. Fatigue tests on uncoated and coated samples were conducted under fully-reversed axial loading in load-controlled condition. The failure mechanism was identified by evaluating the fracture surfaces using scanning electron microscopy. The results showed that both bonding strength and fatigue performance of the coated specimens prepared by using He-gas were significantly higher than those prepared by using N2. Among the N2-sprayed coatings, the bonding strength of on LAS substrates were significantly higher than that of the other surface conditions, and the bonding strength of coatings on GB substrates was superior to that of polished and semi-polished samples. However, the fatigue performance of LAS-coated samples was inferior compared to uncoated samples due to cracks initiating in the coating and propagating into the substrate. The fatigue behavior of GB-coated specimens was similar to the uncoated samples due to delamination of the coating which resulted in stopping the cracks that initiated in the coating.

Coating Failure Prevention for Industrial Valves by Substrate Surface Preparation in Offshore Oil and Gas Industry: A Literature Review

Coating Failure Prevention for Industrial Valves by Substrate Surface Preparation in Offshore Oil and Gas Industry: A Literature Review

Performance of bond strength between ultra-high-performance concrete and concrete substrates (concrete screed and self-compacted concrete): An experimental study

Ultra-high-performance concrete (UHPC) is one of the contemporary overlay materials for repairing and retrofitting of reinforced concrete (RC) members. It possesses excellent compressive and tensile strength, as well as long durability. Nevertheless, the bonding performance between the overlay interface (UHPC) and the substrate concrete must be adequate under various loading, curing, and exposure circumstances. Therefore, this research examined, experimentally, the interfacial bonding behavior of UHPC overlay and two distinct substrates, namely concrete screed (CS) and self-compacted concrete (SCC). Four parameters impacting bond strength behavior, including three different substrate surface preparations, curing conditions, exposure environments, and testing techniques, were used to fulfill the goal of this study. The tests findings revealed that the substrate surface preparation and the exposure conditions had significant effects on the bond behavior of both UHPC-SC and UHPC-SCC while curing conditions seemed not to have any significant effects. The highest bond strength was obtained for specimens having sandblasted substrate preparation technique regardless of the bond test method. However, specimens tested under the bi-surface shear strength technique exhibited high bonding strength with the drill holes substrate preparation technique due to the presence of drilled holes that were being filled with UHPC. The splitting tensile test is a reliable test technique to examine the impact of repeated cyclic exposure samples. As a result of this, a substantial reduction in bond strength of nearly 32%, 55%, and 26% of the UHPC-SCC and 31.84%, 51.5%, and 41.42% for UHPC-SC interfaces for as-cast (AC), drilling hole (DH), and sandblasting (SB) substrate surface preparations, respectively, were obtained. ANOVA was carried out and found to be aligned with the experimental findings.

Influence of Sandblasting and Chemical Etching on Titanium 99.2-Dental Porcelain Bond Strength.

The metal–ceramic interface requires proper surface preparation of both metal and ceramic substrates. This process is complicated by the differences in chemical bonds and physicochemical properties that characterise the two materials. However, adequate bond strength at the interface and phase composition of the titanium-bioceramics system is essential for the durability of dental implants and improving the substrates’ functional properties. In this paper, the authors present the results of a study determining the effect of mechanical and chemical surface treatment (sandblasting and etching) on the strength and quality of the titanium-low-fusing dental porcelain bond. To evaluate the strength of the metal-ceramic interface, the authors performed mechanical tests (three-point bending) according to EN ISO 9693 standard, microscopic observations (SEM-EDS), and Raman spectroscopy studies. The results showed that depending on the chemical etching medium used, different bond strength values and failure mechanisms of the metal-ceramic system were observed. The analyzed samples met the requirements of EN ISO 9693 for metal-ceramic systems and received strength values above 25 MPa. Higher joint strength was obtained for the samples after sandblasting and chemical etching compared to the samples subjected only to sandblasting.

Effects of Substrate Texture and Moisture Conditions on Ultra-High Performance Concrete and Silica Fume Concrete Overlay Bond Strengths

Direct tension tests were conducted to investigate the effects of substrate moisture conditions and texture on ultra-high performance concrete (UHPC) overlay bond strengths. Improper substrate surface preparation can result in inadequate bond strengths and, in severe cases, lack of bond. To demonstrate the importance of surface preparation, pull-off tests were performed on overlaid slabs that had two extreme substrate surface moisture conditions (saturated and dried) prior to overlay application. Saturated slabs had a tined, tined-light sand blasted, or tined-medium sand blasted substrate surface texture. Dried slabs had either a tined or an exposed aggregate surface texture. Saturated specimens with tined, tined-light sand blasted, and tined-medium sand blasted surface textures achieved average bond strengths of 0.924, 1.45, and 1.95 MPa, respectively. Dried substrate surfaced specimens had zero bond strength. Surface moisture conditions that ranged from saturated to dry were also investigated by allowing the substrate surfaces to dry for 15, 30, 45, and 60 minutes prior to application of an UHPC overlay. Tined-light sand blasted specimens with surfaces that dried for 15, 30, 45, and 60 minutes achieved average bond strengths of 2.86, 2.01, 1.59, and 0.165 MPa, respectively. Results showed tined-light sand blasted specimens with proper saturating achieved adequate bond strengths, and properly saturated, tined-medium sand blasted specimens produced excellent bond strengths. Results also exposed the drastic consequences of not maintaining a saturated substrate surface prior to overlay application and delaying overlay application up to 60 minutes can drastically reduce bond strength.