Pixelligent (United States)

Antiwear additives permit energy-efficient lubrication of gearboxes, bearings, and other tribological interfaces. We study zirconia (ZrO2) nanocrystal additives, which readily form protective tribofilms in tribological contacts. Our prior work demonstrated cooperative antiwear performance between ZrO2 and the S- and P-based co-additives in fully formulated hydrocarbon gear oils. Here, we extend that work by examining the growth kinetics of the ZrO2 tribofilms, including the influence of the co-additives. In the boundary lubrication regime for mixed rolling-sliding contacts, the initial phase of ZrO2 tribofilm growth is soon overtaken by removal processes, phenomena whose importance has gone unnoticed in prior work. Tribofilm removal affects the steady-state thickness and morphology of the tribofilm as well as its growth kinetics. The S- and P-based co-additives are incorporated into the ZrO2 tribofilm, and alter the competition between the growth and removal processes, increasing initial net growth rates per contact cycle and contributing to a more polished final interface. This work highlights the significance of removal processes in determining tribofilm antiwear performance, and suggests several routes for improving tribofilm growth kinetics using co-additives.Graphical abstract

Pixelligent’s high-refractive index PixNIL® nanocomposite formulations incorporating ZrO₂, TiO₂, or TiO₂-ZrO₂ coreshell nanoparticles showcase robust nanoimprinting capabilities for surface-relief gratings tailored for extended reality (XR) applications. Thin films exhibit refractive indices ranging from 1.7 to 2.0 @ 589 nm while delivering more than 95% transmission and less than 0.1% haze, attributed to the excellent control over particle size, shape, and surface of the proprietary PixClear® and PixCor™ nanocrystals. While the optical properties of Pixelligent’s nanocrystal dispersions and formulations have been widely reported, less attention has been given to their excellent processability. For XR devices to realize mass market adoption, high yield, robust manufacturing processing, and excellent device reliability must be achieved. In this paper the processability of Pixelligent’s already easy-to-use formulations is reported. PixNIL® ST13A provides a broad soft-bake process window for thin films with a thickness of less than 300nm. Furthermore, PixNIL® formulations extend the usable lifetime of working stamps to over 25 imprints. This paper presents a thorough evaluation of the novel nanoimprint formulation, ST13A, demonstrating significant advancements and introducing a new approach to address key challenges in nanoimprint technologies. The analysis encompasses crucial aspects of the nanoimprinting process, including replication fidelity and soft-bake process window.

Abstract Foam is a promising means to assist in the permanent, safe subsurface sequestration of CO2, whether in aquifers or as part of an enhanced-oil-recovery (EOR) process. Here we review the advantages demonstrated for foam that would assist CO2 sequestration, in particular sweep efficiency and residual trapping, and the challenges yet to be overcome. CO2 is trapped in porous geological layers by an impermeable overburden layer and residual trapping, dissolution into resident brine, and conversion to minerals in the pore space. Over-filling of geological traps and gravity segregation of injected CO2 can lead to excessive stress and cracking of the overburden. Maximizing storage while minimizing overburden stress in the near term depends on residual trapping in the swept zone. Therefore, we review the research and field-trial literature on CO2 foam sweep efficiency and capillary gas trapping in foam. We also review issues involved in surfactant selection for CO2 foam applications. Foam increases both sweep efficiency and residual gas saturation in the region swept. Both properties reduce gravity segregation of CO2. Among gases injected in EOR, CO2 has advantages of easier foam generation, better injectivity, and better prospects for long-distance foam propagation at low pressure gradient. In CO2 injection into aquifers, there is not the issue of destabilization of foam by contact with oil, as in EOR. In all reservoirs, surfactant-alternating-gas foam injection maximizes sweep efficiency while reducing injection pressure compared to direct foam injection. In heterogeneous formations, foam helps equalize injection over various layers. In addition, spontaneous foam generation at layer boundaries reduces gravity segregation of CO2. Challenges to foam-assisted CO2 sequestration include the following: 1) verifying the advantages indicated by laboratory research at the field scale 2) optimizing surfactant performance, while further reducing cost and adsorption if possible 3) long-term chemical stability of surfactant, and dilution of surfactant in the foam bank by flow of water. Residual gas must reside in place for decades, even if surfactant degrades or is diluted. 4) verifying whether foam can block upward flow of CO2 through overburden, either through pore pathways or microfractures. 5) optimizing injectivity and sweep efficiency in the field-design strategy. We review foam field trials for EOR and the state of the art from laboratory and modeling research on CO2 foam properties to present the prospects and challenges for foam-assisted CO2 sequestration.

Abstract The drive to reduce fuel consumption in transportation has encouraged the emergence of low viscosity lubricants to reduce viscous losses in the engine, drivetrain, and other components. However, viscosity reduction increases the risk of surface damage, thus motivating the development of new anti-wear (AW) additives. Capped ZrO2 nanocrystals (NCs) in base oils have been shown to form AW tribofilms within microscale sliding contacts. However, the potential of ZrO2 NCs to protect surfaces subjected to rolling-sliding contact from macroscale damage, such as micro-pitting, remains unexplored. Here, we explore the ability of ZrO2 NCs to form protective tribofilms under harsh conditions using a micro-pitting rig (MPR), consisting of a three ring-on-roller configuration. The experiments were conducted in polyalphaolephin (PAO) base oil, with and without 5 nm diameter ZrO2 NCs, at two levels of slide-to-roll ratio (SRR) (30% and 0%) and at variable test durations up to long durations (119 hours). MPR results showed the use of ZrO2 NCs gives rise to the formation of a tribofilm covering the roller surfaces and decreases the initiation and propagation of micro-pits compared to tests in pure PAO base stock. Transmission electron microscopy (TEM) performed on focused ion beam (FIB) milled cross-sectional samples of the roller surfaces revealed the growth of dense and 50- 100 nm thick ZrO2-based tribofilms independent of (SRR), indicating the potential for robust micro-pitting fatigue protection. Nevertheless, small cracks localized within the near surface region of the roller tested at the most severe conditions (30% SRR and 119 hours) were observed. The initiation of these cracks was directly related to the presence of manganese sulphide (MnS) inclusions in the steel, revealed using TEM combined with energy dispersive spectroscopy (EDS). The results highlight the benefits of the protective tribofilms formed by ZrO2 NCs and suggest approaches for further optimizing their use.

One of the most critical technologies required in XR devices are the optical waveguides applied to the lenses. These waveguides are responsible for taking the image that is projected to the inside of a lens and transmitting it to the other side of the lens, delivering a clear image to the viewer. The key factor that determines a clear and immersive XR visual experience is having a field of view (FoV) as wide as possible. High refractive index formulations are key to increasing the FoV. Here we present characterization data of PixNIL™ nanoimprintable formulations that incorporate PixClear® high refractive index products. Films made with Pixelligent’s PixClear® TiO2 nanocrystals with a mean particle diameter of 20 nm and dispersed in an acrylate-based binder demonstrate refractive index values as high 1.96 at 589 nm. In addition, these films maintain high transparency in the visible light spectrum (400 – 700 nm) and demonstrate both low haze and low absorbance. The PixNIL™ formulations can be applied using nanoimprint lithography (NIL) to create optical structures that are key to enabling the widest FoV waveguides.

High refractive index (RI) nanocomposites have properties which surpass traditional polymers while maintaining manufacturability. Nanocrystal nanocomposites, when inkjet‐printed, are useful to many displays and lighting components and aid the development of next generation information devices and lighting fixtures. This paper demonstrates inkjet printing capabilities using high RI, highly transparent PixClear® ZrO 2 nanocrystal dispersions and nanocomposites.