Why NKR® fibers are different?
Because they are…
- Single Crystal Fibers.
- Grown in the C-axis direction.
- Of alpha-alumina (corundum).
- With a very high aspect ratio.
- Increased strength.
- High thermal stability.
- Excellent performance in corrosive environments.
- Significant reduction of creep and fatigue damage.
- Significant increase in toughness.
- Degree of flexibility adaptable on demand.
- Electromagnetic transparency.
- Processing flexibility.
- Crystal Type: Alpha (sapphire) (Single Crystal).
- Diameter, μm: 0.1-5.
- Length, μm: 5-500.
- Density, g/cm3: 4.
- Purity, wt %: ~99 Al2O3.
- Chemical composition: >99.7% Al2O3.
- Tensile Strength: >6 GPa.
- Aspect Ratio: >103.
- Electrical: Insulator.
- Melting point: 2050º C.
- Environmental Resistance: Flammability, Fresh Water, Organic, Solvents, Oxidation, Sea Water, Strong Acid, Strong Alkalis, Wear...
Neoker has obtained the following certifications:
Neoker also is in the final stages of implementation of the following systems of quality management:
- • R&D Certification: UNE 166001 and RD1432/2003.
¿What are the NKR® fibers?
NKR® single crystal alumina fibers improve the thermal performance and the chemical and mechanical properties of advanced composites. In addition, NKR® fibers provide benefits superior to those of other substitute materials:
Comparison of NKR® fibers properties vs. substitute materials*
|Properties||NKR® Fibers(Alumina Single Crystal Fibers)||Alumina Polycrystal Fibers||SiC||Carbon Fibers|
|Purity: Present Phases||One phase.||Two phases, one of them limiting the performance.||One phase.||One phase.|
|Cristaline Structure||Single crystal.No grain growth.||Polycrystal.Grain boundaries: creep.||Single crystal.No grain growth.||Single / polycrystal|
|Thermal||Very high thermal stability in all conditions. Service Tª: 1500º C.||<1200º C||Very high thermal stability. Service Tª: 1500º C, except in corrosive environments.||Very high thermal stability. Service Tª: 1500º C, except in corrosive environments.|
|Chemical||Stable even with strong acids, alkalies, corrosion environments…||Not stable.||Stable only with some acids. Not stable in presence of Oxygen, H2O, etc.||Stable only with some acids. Not stable in presence of Oxygen, H2O, etc.|
|Mechanical||Very high.||Low.||Very high, but not time-consistent.||Very high, but not time-consistent.|
*Reference: Krenkel, Walter (Ed.): Ceramic Matrix Composites. Fiber Reinforced Ceramics and their Applications. 2008, Wiley-VCH.
Uses of NKR® fibers
NKR® fibers are indicated for:
- Aggressive environments (acids or bases).
- Combustion environments (engines, turbines …).
- A wide range of working temperatures: since its performance is stable from room temperature to high temperatures (melting point 2000° C, stable up to 1700° C, even in reducing atmospheres).
- Improved creep resistance in MMC’s and CMC’s.
- Increased hardness and abrasion resistance.
- Improved impact resistance.
For more information on the different applicationsof the NKR® fibers, please visit Industries.
Forms of use
- As part of MMC, CMC o PMC:
- Used as a powder that is mixed with the original raw materials.
- Developed as preforms for subsequent infiltration.
- Applied to the composite through surface treatments.
- As an insulator able to withstand high temperatures, aggressive environments and friction.
What formats are sold?
- Fibers: Lower bulk density. Suitable for surface coating because of its insulating effect.
- Fiber powder: Higher bulk density. Suitable for processing composite materials.
What is our intellectual property?
Neoker has designed and developed the processes for industrial manufacturing of the NKR®fibers. These processes are protected by several patents owned by Neoker.