Microindentation Technique Research Articles

Creep and fracture of UHSC — A microindentation study

Creep and fracture behaviour of normal strength concrete was investigated by various researchers whereas, research on creep and fracture of Ultra-High-Strength Concrete (UHSC), i.e., concrete with 28-day compressive strength greater than 100MPa is scanty. Also, a detailed investigation of the creep–fracture interaction of UHSC has not been conducted.This study aims at examining creep and fracture of UHSC cement paste mixes (w/b = 0.20) with varying levels of silica fume (SF) replacement (0%, 20%, and 40%) at different ages (3d, 7d, 28d, 90d) using microindentation technique. Two different holding durations, namely 5 s and 180 s, were considered in the indentation test. The findings revealed a noteworthy variation in estimated fracture toughness (Kc) between the two dwelling periods. Longer sustained loading times (180s) indicated a decrease in fracture toughness for all ages considered, suggesting progressive internal cracking during creep phase. Attempt has been made to investigate the interaction effect.

DAMAGE ACCUMULATION IN THE V95\3% TIC METALMATRIX COMPOSITE DURING DEFORMATION AT HIGH TEMPERATURES

Damage accumulation in a dispersion-strengthened metal matrix composite was studied at deformation temperatures ranging between 300 and 500°C. The composite has the V95 alloy matrix (the Russian analogue of the 7075 alloy) reinforced by titanium carbide (TiC) particles in a volume content of 3%. The composite was made by ex-situ liquid-phase technology. Damage calculation is based on the data of the evolution of the elastic modulus value obtained by the instrumented microindentation technique. It has been experimentally found that, under compression at the macroscale, the composite has the best plasticity at a temperature of 400°C. The plasticproperties at a deformation temperature of 500°C are significantly lower than at 300 and 400°C. ranging from 300 to 500°C and strain rates ranging between 0.1 and 10 s-1. The paper presents experimental dependences between flow stress and strain for temperatures ranging from 300 to 500°C and strain rates ranging between 0.1 and 10 s-1. Based on these data, finite element simulation of specimen compression was carried out, which makes it possible to describe the influence of loading conditions on the evolution of the stress state characterized by the Lode-Nadai coefficient mσ and the σ/T ratio, where σ is mean normal stress and T is tangential stress intensity.

Anisotropic fracture energy and toughness of single crystal gallium arsenide by microindentation

Although single crystal gallium arsenide (GaAs) is a technologically important semiconductor material, its mechanical behavior is poorly understood. In this study, the Vickers microindentation technique was leveraged with a quantitative fractographic approach to determine the fracture energy and toughness corresponding to various crystal planes. Cracks preferentially propagated along the {110} planes associated with the primary crack system {110} / 〈110〉. The normalized fracture toughness was used to calculate the directional fracture energy on the {001} plane and was consistent with a theoretical model based on calculating the number of broken bonds.

On the chemo-mechanical evolution process of high-volume slag cement paste

This study investigated the evolution process of high-volume slag cement (HVSC) paste from a chemo-mechanical standpoint. HVSC specimens with a 70 w.t. % slag replacement rate were studied at various ages. Evolution of phase assemblage, microstructure development, and micromechanical properties were analyzed using TGA/XRD/MIP/SEM-EDS and nano-/micro-indentation techniques. A two-scale micromechanical model was built to predict the effective elastic modulus based on the nanoindentation results. Key findings include: 1) Between 7 and 28 days, the formation of calcium silicate hydrate (C-S-H) gel phase improves the effective elastic modulus by filling capillary pores; 2) From 28 to 90 days, the phase assemblage and microstructure remain stable, with a transition from low-density to high-density C-S-H; 3) Between 90 days and 2 years, slag rims produced by slag grains result in increased elastic modulus; 4) The two-scale micromechanical model, combined with nanoindentation data, accurately predicts the effective modulus of HVSC composites, although the unhydrated slag grains-hydrated cement matrix interface may cause an overestimation at an early age. With longer curing time, this interface disappears owing to the continuous hydration of large slag particles and therefore a good match is found between the modelling and experimental results.

Structural and Mechanical Properties of DLC/TiN Coatings on Carbide for Wood-Cutting Applications

In this work, the diamond-like carbon and titanium nitride (DLC/TiN) multilayer coatings were prepared on a cemented tungsten carbide substrate (WC—3 wt.% Co) using the cathodic vacuum arc physical vapor deposition (Arc-PVD) method and pulsed Arc-PVD method with a graphite cathode for the deposition of TiN and carbon layers, respectively. The structural and mechanical properties of the prepared coatings were studied, and different techniques, such as scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy, and microindentation techniques investigated their microstructure, composition, and phases. The prepared coatings had a multilayer structure with distinct phases of DLC, TiN, and carbide substrate. The potentiodynamic polarization method (PDP) was performed for the DLC/TiN multilayer coatings in 3% NaCl solution to evaluate the corrosion resistance of the prepared coatings. It has been shown that the DLC layer provided the coating with a polarization resistance of 564.46 kΩ. Moreover, it has been demonstrated that the DLC/TiN coatings had a high hardness of 38.7–40.4 GPa, which can help to extend the wood-cutting tools’ life.

#6641 BONE MATERIAL STRENGTH INDEX AND DUAL ENERGY X-RAY ABSORPTIOMETRY IN EVALUATION OF BONE HEALTH IN AUTOSOMAL POLYCYSTIC KIDNEY DISEASE

Abstract Background and Aims Bone material strength measured with the use of impact microindentation technique (OsteoProbe®) has emerged recently as potentially beneficial tool in evaluating bone quality in metabolic bone disorders. Patients with autosomal polycystic kidney disease (ADPKD) carry an increased risk of skeletal complications, both due to deficiency of polycystins and development of chronic kidney disease-mineral bone disorder (CKD-MBD). In our preliminary study, we found that bone material strength index (BMSi) associated with bone mineral density (BMD) measured with the use of dual energy X-ray absorptiometry (DXA) in chronic kidney disese patients (CKD). The aim of the present study was to find if the same applies to patients with ADPKD. We evaluated bone health by measuring BMSi and performing DXA in patients with ADPKD. Method BMSi was measured (OsteoProbe®, Active Life Scientific, USA) in 64 adult patients (37 men, mean age 43 years) with ADPKD in CKD stages G1-4. The measurement of BMSi compared the resistance to impact of microindentation in bone and reference material. After applying local anaesthesia, we impacted the cortical bone in the midshaft tibia in 10 different points. BMD was measured using Hologic Discovery Wi densitometer in multiple sites: lumbar spine, hip, 1/3 distal non-dominant forearm and whole-body. Trabecular bone score (TBS) was calculated using Medimaps TBS iNsight software. Results Mean values of BMSi, TBS and BMD are presented in the Table 1. BMSi in ADPKD patients was lower than average value observed in healthy individuals (85 men and 80 women). A positive linear relationship between BMSi and BMD was found in all of the examined sites with the highest standardized regression coefficient for 1/3 distal forearm (R2 = 0.315, beta = 0.57, p < 0.001) and weakest for lumbar spine (R2 = 0.003, beta = 0.33, p = 0.003). There was no association between BMSi and TBS. Conclusion This is the first report on BMSi in ADPKD patients. In agreement with the notion of a distinct bone phenotype in ADPKD, we observed a median bone material strength index in patients with ADPKD that was lower than the reference value. BMSi associated with BMD, but not with TBS. However, the association with BMD overall is weak, with BMD explaining only 3 to 31% of the variability of BMSi. This observation suggests complementarity and warrants additional studies investigating whether BMSi associates with hard bone endpoints, independent of BMD.

The influence of metallic particulate inclusions on the mechanical and thermal performance of 3D printable acrylonitrile-butadiene-styrene/thermoplastic polyurethane fused polymer blends

Acrylonitrile butadiene styrene (ABS) shows exceptional mechanical behavior, however, the application of ABS for manufacturing thin parts has been limited because of its significantly lower melt fluidity. Thermoplastic polyurethane (TPU), on the other hand, has acceptable melt fluidity, but its mechanical performance is limited when compared to ABS. This paper combines these two polymers and incorporates elongated iron powder particulates as a reinforcing agent to manufacture a cost-effective yet performance-enhanced blended polymer filament for 3D printing. The melt-mixing approach was followed for blended polymer filament manufacturing. The thermal performance of the extruded filaments was evaluated using differential scanning calorimetry (DSC). The glass transition and melting temperatures were found to be slightly higher for the particulate-reinforced samples when compared to the control unreinforced ABS/TPU blend. This is attributable to the fact that the inclusions limit the mobility of the structure therefore it requires more energy to break down the molecular structure. The tensile strength of the filaments was obtained using a uniaxial tension experiment whereas the fracture toughness of the 3D printed parts was determined using the microindentation technique. The tensile strength and fracture toughness was found to be increasing with an increase in iron powder dosage by up to 5 %. The results reflect that appropriate dispersion of iron particulates is required to achieve the desired performance enhancement. Overall, the findings of this paper can potentially lead to various cost-effective and efficient means for performance enhancement in the manufacturing of 3D printable blended polymer composite filaments.

Fracture Testing of Lithium‐Ion Battery Cathode Secondary Particles in‐situ inside the Scanning Electron Microscope

AbstractFracture of cathode secondary particles is a critical degradation mechanism in lithium‐ion batteries. The microindentation strength of LiNi0.8Mn0.1Co0.1O2 secondary particles is measured in situ in the scanning electron microscope (SEM), enabling dynamical imaging of fracture. Crack propagation is intergranular between primary particles when induced by compressing between flat platens (analogous to calendaring), and with a cono‐spherical indenter (representing particle‐particle contact). Fracture occurs directly beneath the cono‐spherical tip and at the centre of secondary particles when compressed between flat platens. Finite element modelling of stress states provides insight into the dependence of fracture load upon cohesive strength and particle toughness. Secondary particle indentation strength decreases with increasing secondary particle size, with cycling, and with increasing state of charge. The indentation strength decrease is greatest in earlier stages of delithiation. The novel microindentation technique allows assessment of strength and toughness of different cathode morphologies, aiding prediction of optimal particle structure and processing conditions.

Which crystal structure is present on the surface of Ti[formula omitted]CrAl compound - a deduction from electronic structure measurements and calculations

In this report, we study the Ti2CrAl compound, a Heusler compound that was believed to exhibit half-metallic ferromagnet (HMF) or even spin gapless semiconductor (SGS) properties. Here, we present our investigations of electronic structure by means of X-ray Photoelectron Spectrosocopy (XPS), X-ray Absorption Spectroscopy (XAS) and band structure calculations. Our results show that the surface has the same regular Heusler structure as the bulk and not the inverted Heusler structure as it was assumed before. We noted that the sample is very hard, therefore we present here measurements of microhardness and elastic modulus using microindentation technique. In addition, thermopower calculated from the band structure for both structural models using Boltzmann equation is compared with our experimental measurements.

Improving the Creep Resistance of Hardened Cement Paste through the Addition of Wollastonite Microfibers: Evaluation Using the Micro-Indentation Technique

This paper evaluates the creep behavior of wollastonite-microfiber-reinforced hardened cement paste. A parametric study was performed for cementitious mixtures with partial replacement of cement using wollastonite. The samples were subjected to uniaxial compression and microindentation experiments. The compressive strength significantly improved by up to 30% for the mixture containing 10% wollastonite fiber. Microindentation experiments were performed to evaluate the creep response and time-dependent performance of both the control and the wollastonite-fiber-reinforced samples. Approximately 36% increase in creep modulus was observed with 10% wollastonite fiber content. This indicates a significant improvement in creep behavior, which can be attributed to the micro-reinforcing effect of the fibers. No significant impact was observed for time characteristic of creep with the incorporation of wollastonite fibers. Overall, the study establishes a cost-effective, sustainable, and efficient route to enhance the creep behavior of hardened cement paste for a wide range of infrastructural applications.

Residual stresses and distortions in additive manufactured Inconel 718

ABSTRACT Direct energy deposition is an additive manufacturing technique, follows layer-wise deposition to avail design freedom and minimizes material wastage. Despite the unique advantages, repeated heating and cooling induces thermal strains in the components. The present investigation is to understand the thermal-induced distortions and residual stresses in Inconel 718 components fabricated through direct energy deposition. The distortions and temperature measurements are carried out in situ and residual stresses are measured using micro-indentation technique. The distortions are increasing with number of layers, and the distortion rate is varying along the height of deposition. The temperature data indicated rapid heating and cooling. The residual stresses measured are compressive in nature, and are approximately 40% of yield strength in magnitude. The ultimate strength, yield strengths are 800 ± 30 MPa, 580 ± 50 MPa respectively, and maximum hardness obtained is 349 HV. Microstructure Characterizations showed continuous growth of columnar dendrites through multiple layers, and Nb segregation at interdendrites.

The impact of free-radical stabilization techniques on in vivo subsurface mechanical properties in highly cross-linked polyethylene acetabular liners.

Highly cross-linked polyethylene (HXLPE) for total hip arthroplasty was developed to improve wear resistance in vivo and associated complications in comparison to ultrahigh molecular weight polyethylene. This material typically goes through various free-radical stabilization techniques by remelting, single-annealing, or sequentially annealing the polyethylene to improve in vivo oxidation and wear properties. The purpose of this study is to determine if there is evidence of subsurface microhardness changes in retrieved HXLPE liner at the rim and articular subsurface after extended in vivo time that could be associated with oxidation and its effects on mechanical properties and implant integrity. Retrieved HXLPE liners were chosen based on peak subsurface Fourier transform infrared spectroscopy oxidation values. Each was mechanically tested for subsurface microhardness at both the rim and articular surface using a validated microindentation technique. Rim testing demonstrated a decrease in mechanical integrity that corresponded to higher subsurface oxidation values regardless of the free-radical stabilization technique. At the articular surface, a decrease in mechanical integrity was observed near the surface corresponding to peak oxidation and Vicker's hardness, which decreased with increasing depths. This was found in all groups, with the exception of the single-annealed liners, which demonstrated decreased mechanical integrity trends at greater depths between 1.0 and 2.0 mm. Our results suggest that subsurface mechanical properties do change in vivo for certain implants. Though it is likely that the mechanical failures are multifactorial, we have shown that mechanical property degradation of HXLPE liners does occur with long-term in vivo exposure and should be considered a possible risk factor.

Measuring Cell Mechanical Properties Using Microindentation.

Quantifying cell mechanical properties is of interest to better understand both physiological and pathological cellular processes. Cell mechanical properties are quantified by a finite set of parameters such as the effective Young's modulus or the effective viscosity. These parameters can be extracted by applying controlled forces to a cell and by quantifying the resulting deformation of the cell.Microindentation consists in pressing a cell with a calibrated spring terminated by a rigid tip and by measuring the resulting indentation of the cell. We have developed a microindentation technique that uses a flexible micropipette as a spring. The micropipette has a microbead at its tip, and this spherical geometry allows using analytical models to extract cell mechanical properties from microindentation experiments. We use another micropipette to hold the cell to be indented, which makes this technique well suited to study nonadherent cells, but we also describe how to use this technique on adherent cells.

Microstructural characteristics and mechanical properties of Si-B alloys for functional and structural ultra-high temperature applications

Silicon boron alloys have been recognized as important materials for e.g. a direct usage in ultra-high temperature latent heat thermal energy storage systems or as a batch materials for processing boron enhanced silicide-based composites. In this work, we put new experimentally driven insights on a structure of selected Si-B binary alloys. For this reason, four Si-xB alloys (x = 2.5; 8, 13.5; 86 (at%)) were fabricated from pure elements by using a crucible-less electric arc melting technique. Nominal compositions of the alloys were selected in accordance to Si-B phase diagram as hypoeutectic, eutectic, hypereutectic and corresponding to the stoichiometric composition of SiB6 intermetallic phase, respectively. The fabricated Si-xB alloys were subjected to a detailed structural characterization. Additionally, a hardness, elastic moduli and fracture toughness of each phase constituent were examined through a micro-indentation technique. A co-existence of various silicon borides, namely SiB4, SiB6 and SiBn, has been experimentally documented. Obtained results allows receiving a description of each alloy in terms of microstructure, crystal structure and mechanical properties of involved phases. It was found that mechanical properties (both microhardness and Young modulus) increases with raising boron content in recognized Si-B phases. The fracture toughness of silicon borides assessed through indentation experiments was found to be in the rage of 2.13–3.29 MPa·m1/2.

Compositional design and in vitro investigation on novel Zr–Co–Cu–Ti metallic glass for biomedical applications

Zr–Co–Cu–Al based metallic glasses (MGs) are potential material for making surgical equipment due to their ultra-high strength. However, presence of elemental Al in these alloys is not desirable due to biotoxicity. To counter this problem the present study is undertaken to design metallic glass forming composition by replacing Al with Ti. Design strategy adopted is based on thermodynamic modelling by rationalizing the effect of chemical enthalpy and atomic mismatch entropy along with statistically controlled atomic arrangement through configurational entropy. The rapid solidification technique was used to synthesize MG in melt spun ribbon form. The structural nature and glass stability of the ribbon are confirmed by X-Ray diffraction, transmission electron microscopy and differential scanning calorimetry. Corrosion response of the MG is thoroughly investigated using potentiodynamic polarization and electrochemical impedance spectroscopy in a simulated body fluid (SBF) environment. The mechanical property of MG is evaluated using microindentation technique. Improvement in corrosion resistance is observed in all the SBF solutions along with in vitro biocompatibility study using MG-63 cell viability experiment.

Evaluation of residual stress in thick metallic coatings using the combination of hole drilling and micro-indentation methods

Plasma spraying is commonly used to deposit thick metallic coatings. The high deposition temperature and complex interaction of the process parameters result in tensile residual stresses in thick metallic layers. Tensile residual stresses are widely known to affect the integrity of metallic coatings. The present study uses a combination of hole drilling and micro-indentation techniques to evaluate the residual stress developed in Ni-based metallic coatings deposited on stainless steel substrate using a direct current plasma spray torch. The metallic coating samples are first characterized by microscopy, surface roughness measurement, micro-indentation, and scratch tests before through-thickness residual strain measurement via the incremental hole-drilling method. The residual stress in the metallic coating layers is evaluated from the incremental strain measurements and micro-indentation curves. The studies show that the residual stress can be reliably predicted using the combination of hole drilling and micro-indentation measurements. It is found that tensile residual stresses are developed across the depth of both NiCrAl and Ni–20Al coatings. The variation of the tensile residual stresses across the depth is nonlinear and almost equibiaxial. The residual stress strongly influences the adhesion strength of the thick metallic coating layers.

Using micro-indentation to determine the elastic modulus of shale laminae and its implication: Cross-scale correlation of elastic modulus of mineral and rock

Lamina is the smallest megascopic layer in a sedimentary sequence. Different laminae are usually distinguished by various mineral compositions and different thicknesses ranging from tens of micrometers to several millimeters, which significantly affects shale deformation and fracture extension during shale gas/oil exploitation. Nevertheless, due to the minute thickness of laminae, it is hardly possible to determine their elastic moduli by traditional standard mechanical methods and detailed mechanical properties of laminae have been rarely reported. In this work, we studied the elastic modulus differences of laminae in continental shale using micro-indentation technique and scanned electronic microscope (SEM) equipped with automatic mineral identification and characterization system (AMICS). The results demonstrate that the elastic moduli of laminae are highly heterogeneous and can be classified into three types: the stiffer layer, the intermediate layer, and the soft layer, corresponding to the pyritic lamina, the sandy lamina, and the organic-rich lamina, respectively. Additionally, the elastic modulus of lamina excellently correlates with mineral compositions, with the weight coefficients of different minerals on the composite elastic modulus of lamina differing greatly. With the combination of the thickness and the elastic modulus of every single lamina within the shale, it is accessible to obtain the elastic modulus of shale by analytical solutions. Therefore, an efficient method is proposed to characterize the cross-scale elastic modulus from nano/submicron mineral to macro rock based on the mineral components and geometric analysis of laminae, which is rapid and economically feasible, particularly helpful when neither sufficient samples nor logging data are available.

Study of some thermo-mechanical parameters in Se70Te30-xMx (x = 0, 2; M = Cd, Ag, and Zn) alloys

Vickers microhardness has been determined by performing micro-indentation experiments on Chalcogenide glasses (ChGs) of Se70Te30, and Se70Te28M2 (M = Cd, Ag, and Zn) alloys using micro-indentation and optical microscopic techniques. Vickers micro-hardness is directly observed by the diagonal lengths of the indentation marks of a pyramidal diamond indenter. Thermally-induced glass transition was noticed by the DSC technique. Mechanical property such as modulus of elasticity (E), is calculated by well-known empirical relations. The minimal energy of micro-void (Eh), micro void volume (Vh), and covalence character of the glassy system are discussed in terms of microhardness (Hv). Physical parameters i.e., overall mean bond energy, density, molar volume, and compactness have been also carried out.

Are Bone Metabolism and Bone Material Strength Evaluations Worthwhile?: Commentary on an article by Tamara D. Rozental, MD, et al.: "Longitudinal Changes in Serum Markers of Bone Metabolism and Bone Material Strength in Premenopausal Women with Distal Radial Fracture".

Commentary The article by Dr. Tamara D. Rozental and colleagues introduces us to 2 innovative methods to improve our understanding of bone strength and fracture-healing biochemistry that maybe relevant to clinical practice. Bone mineral density (BMD) is the standard for determining bone quality and fracture risk but does not define the structural and mechanical properties of bone1. Impact microindentation provides information on the material properties of cortical bone that we as orthopaedic surgeons need in order to improve our choice of fixation strategy2. Markers of bone metabolism (MBM) have been used to assess the results of osteoporotic treatment but have not been applied to the non-osteoporotic patient to assess fracture healing or to predict potential osteoporosis3,4. Impact microindentation is a minimally invasive technique that measures the ability of the tibial cortex to resist a standardized impact force. This measures the bone’s material quality, which is the interaction of the bone’s mineral and organic elements to resist failure. This technique might allow for a better determination of the ability of bone to hold implants that are used for fracture fixation (for example, the ability to achieve screw purchase). A greater understanding of such variables would facilitate fixation decisions, including the potential need to augment fixation with use of locking screws or bone substitutes. In this study, the microindentation technique did not prove valuable in assessing bone quality, but the investigators demonstrated that the test was possible to administer in a clinical setting. MBM have demonstrated promise as markers of the healing response following the treatment of a fracture5. Sclerostin (a glycoprotein produced by osteocytes) and Dickkopf 1 (DKK1) both decrease bone formation were initially increased but then both dropped to low levels allowing the healing response to occur. Tartrate-resistant acid phosphatase (TRAP) and C-terminal telopeptide (both of which are indicators of osteoclastic activity) peaked early, indicating the need for bone removal secondary to fracture site necrosis. Bone-formation markers such as N-terminal extension propeptide of type-I collagen (P1NP) and bone-specific alkaline phosphatase (BSAP) increased throughout the healing phase. These longitudinal results are evidence that, in premenopausal women, the biochemistry of fracture healing can be evaluated. This study provides the impetus to evaluate whether MBM can determine problems in fracture healing earlier than radiographic evidence and also whether MBM can serve as an indication of early osteopenia and osteoporosis in premenopausal women6. This article had a number of strengths. Patient selection was appropriate (although it was limited to a specific group of premenopausal women with a distal radial fracture). The fractures were classified with use of an acceptable system that can be used to determine severity on the basis of the mechanism of injury (i.e., high or low energy). Finally, the study included both operatively and nonoperatively managed patients, with the former demonstrating an elevated BSAP. This article also had also several areas of concern. MBM vary depending on patient activity and the time of day when the samples are taken. The authors acknowledge this limitation, but it is important for the reader to understand that the controls were only sampled once, so any assumption regarding longitudinal MBM levels may not hold. Another issue is that there is no consensus on what constitutes a meaningful clinical difference in these results. As this study is the first to measure MBM during fracture healing, one is unsure of what these results mean. It is obvious that the results appear to coincide with our understanding of fracture healing, but this relationship has not been proven. Although this study has limitations, including a small sample size in a very specific patient population, it opens the door to a better understanding of fracture healing. Orthopaedic surgeons, particularly those specializing in fracture care, should consider this study as an impetus to further investigate the physiology and biochemistry of fracture healing.

Effects of environmental conditions on the micro-mechanical properties of formulated waterborne coatings

Waterborne colloidal polymer coatings are widely used in architectural and agricultural applications where they are subject to challenging environments, such as extremes of temperatures and relative humidities (RH). This research investigates the effects of adding two common co-formulants, poly(acrylic acid) (PAA) and xanthan gum (XG), to waterborne polymer composite coatings in these environments. The mechanical properties of the resulting coatings are of particular interest. Hardness, creep and tack properties of thick (~400 μm) formulated model coatings were characterized using a micro-indentation technique operating in a single cycle within a bespoke environmental chamber. Measurements were made at three temperatures (16, 20 and 30 °C), which span the glass transition temperature (Tg) of the acrylic copolymer binder, and over three RH values of 10%, 43%, and 90%. The creep data were analysed using the Burgers model to extract characteristic viscoelastic properties. The tack was found by recording the force when withdrawing the probe from the sample and using it to obtain nominal stress (knowing the indentation depth and probe geometry) during the indenter's withdrawal and hence the work of adhesion (WAdh) to detach from the coating. Tack adhesion is completely lost below the binder's Tg but increases when the ambient temperature increases. In formulated coatings, both the tack and creep deformation increase as the relative humidity increases, and this trend is observed at each temperature. There is no evidence from thermal analysis for plasticization of the acrylic polymer by moisture sorption, but the two co-formulants are hydrophilic. The observed softening of the coatings at high RH can be attributed to water sorption in the components. The presence of glassy PAA has the effect of raising the hardness of glassy coatings, but only at low RH when there is no plasticization by water. The addition of hydrophilic XG surprisingly reduces tack adhesion while also raising the viscosity of the coating. These findings will inform the formulation of waterborne colloidal coatings to function in a range of environments.