Silica deposition on zirconia via room-temperature atomic layer deposition (RT-ALD): Effect on bond strength to veneering ceramic.

PURPOSE: To develop and to characterize a hybrid interface between yttria-stabilized zirconia (Y-TZP) transformed layer and silica-based nanofilm to enable a better bonding between Y-TZP and a veneering ceramic. MATERIAL AND METHODS: Sixty-six fully-sintered rectangular Y-TZP specimens were distributed into 6 groups, according to the surface treatment applied: C (control): no treatment; Al: 27 µm-alumina particle abrasion; Ht: hydrothermal treatment in autoclave for 15h; Si20: 20 cycles of silica deposition using room-temperature atomic layer deposition (RT-ALD); Si40: 40 cycles of RT-ALD; Ht + Si40: hydrothermal treatment followed by 40 cycles of RT-ALD. RT-ALD was performed by the sequential exposure of specimens to vapor of tetramethoxysilane orthosilicate (TMOS) and ammonium hydroxide (NH4OH). Y-TZP surface wettability and shear bond strength (SBS) between Y-TZP and the veneering ceramic were analyzed for all groups after surface treatments. One-way ANOVA and Tukey's HSD test were used for data analysis (p ≤ 0.05). RESULTS: The highest contact angle was observed for the control group (64.46 ± 6.09 θ), while the lowest values (p < 0.001) were presented after Si20 (29.85 ± 4.23 θ) and Si40 (30.37 ± 5.51 θ) treatments. Hydrothermal treatment (49.3 ± 2.69 θ) and alumina abrasion (45.84 ± 4.12 θ) resulted in intermediate contact angle values. The highest SBS values were observed for Al (16.74 ± 1.68 MPa) and Ht (15.27 ± 2.11 MPa) groups (p < 0.018). Groups Si20 (9.66 ± 1.22 MPa), Si40 (9.33 ± 2.11 MPa), Ht + Si40 (9.37 ± 1.02 MPa) and C (12.54 ± 2.64 MPa) all resulted in similar SBS results (p > 0.998). CONCLUSION: The experimental treatments proposed enhanced surface wettability, but shear bond strength between Y-TZP and veneering ceramic was not improved. Alumina particle-abrasion improved SBS values while a decrease in wettability was observed.

Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity.

Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging. Inspirations from natural nonwetting structures, particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air-liquid interface. Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis, failure under pressure and upon physical damage, inability to self-heal and high production cost. To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach-inspired by Nepenthes pitcher plants-is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert 'slippery' interface. This surface outperforms its natural counterparts and state-of-the-art synthetic liquid-repellent surfaces in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1-1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.