Aerogel + Microsphere Dual-Scale Insulation Additive System
CAS Number: 7631-86-9 / 65997-17-3
A two-component insulation additive system combining nano-porous silica aerogel powder (CAS 7631-86-9) and hollow borosilicate glass microspheres (CAS 65997-17-3). The system achieves 0.030–0.035 W/(m·K) in a 1.5 mm waterborne coating — performance within 15% of pure aerogel coatings at approximately 1.8× the cost of microsphere-only formulas, versus 3.2× for pure aerogel. Mechanism: aerogel powder (2–50 nm pores) suppresses gas-phase heat transfer via the Knudsen effect at nano-scale; microspheres (25–80 µm diameter, sealed hollow) block convection and break up binder conduction paths at micro-scale. The two additives target different heat transfer mechanisms with no functional overlap — the conductivity reduction is cumulative. Recommended starting formula for general insulation coatings: 8 wt% aerogel medium grade (20–100 µm, hydrophobic) + 15 vol% HL38 microspheres in waterborne acrylic binder.
Technical Specifications
| mixing shear | Low-shear < 500 rpm; add microspheres first, aerogel last |
| aerogel loading | 5 – 15 wt% of total wet formula |
| compatible binders | Waterborne acrylic, epoxy, silicate, silicone |
| microsphere loading | 10 – 25 vol% of total wet formula |
| service temperature | −200 to +650°C (aerogel component) |
| cost index vs pure aerogel | ~0.56× (44% of pure aerogel cost premium) |
| system thermal conductivity | 0.030 – 0.035 W/(m·K) at 1.5 mm DFT |
| microsphere grades recommended | HL34 – HL42 (crush strength 3,000 – 6,000 psi) |
| cost index vs microspheres only | ~1.8× at 15 vol% MS + 8 wt% aerogel |
| aerogel particle size recommended | 20 – 100 µm (medium grade) |
Applications
- Industrial pipe insulation coatings — replaces mineral wool wrapping on above-ground pipelines at 80–200°C
- Building exterior wall insulation render — single-layer 20–30 mm achieves EPS-equivalent performance
- LNG and cryogenic tank cold insulation — hydrophobic aerogel prevents moisture ingress at −160°C
- EV battery pack inter-module thermal barriers — passive thermal runaway containment without added fireproof interlayers
- Marine anti-condensation and hull insulation coatings
- Waterborne and solvent-based formulations for coating formulators adding an insulation layer to existing product lines
Key Features
- Addresses two heat transfer mechanisms simultaneously — no functional overlap between components
- 0.030–0.035 W/(m·K) in 1.5 mm film: performance within 15% of pure aerogel at 44% of cost premium
- Aerogel Knudsen nano-pores (2–50 nm) suppress gas-phase conduction that microspheres cannot block
- Microspheres block convection and break solid binder conduction paths that aerogel alone cannot cost-effectively manage
- Compatible with existing waterborne acrylic formulas — add both components without reformulating binder
- Low-shear mixing protocol preserves aerogel nano-pore structure and microsphere shell integrity
- Hydrophobic aerogel grade available for waterborne systems — prevents re-agglomeration during storage
- System components available as combined sample set for formulation development
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CAS Number
7631-86-9 / 65997-17-3
Category
New MaterialsAvailability
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