General Specifications of the SFA 2000 and Main Attachments
The following values are approximate, and should be calibrated for each instrument and attachment before use as described in the Users Manuals. It is also advisable to recheck some calibrations periodically. This is because some properties, for example, of piezo-electric crystals, can depend not only on the temperature, but also on the humidity, time and usage (aging and previous history effects).
SFA 2000 Basic Unit
- Normal distance resolution: 0.1 nm (1 Å).
- Sensitivity of measuring normal and adhesion forces: 10 nN.
- Lateral distance resolution: 1µm.
- Maximum compressive pressure previously attained (using curved surfaces of radii 0.52 mm and a thin layer of hard glue): 0.5 GPa (5,000 atm).
- Thermal drift: < 0.1 Å/sec (after 1 hr equilibration in a room or enclosure that is temperature stabilized to ±0.1℃).
Friction Device (semi-conductor gauges)
- Sensitivity of measuring lateral, shear, and frictional forces: 10-5 N = 1 dyne.3
- Friction spring stiffness: typically 104 N/m = 107 dyn/cm (large range of stiffness available).
- Lateral distance sensitivity: approx 10Å = 1 nm.3
- Resolution of measuring Friction Coefficients: 0.0001.3
- Range of reciprocating sliding/shearing distance: ±2.5 mm (5 mm peak-to-peak). A special rotating disk substrate now allows for continuous rotational motion.
- Range of lateral sliding speeds: 10-8 to 1 cm/s (a special high-speed attachment now allows for speeds of >10 m/s.
- Maximum shear rates attainable: 105 s-1 in squeeze mode (higher rates attainable in shearing/sliding mode depending on the test fluid).
- Recommended range of driving frequencies: 10-6 to 250 Hz.
- Resonant frequency of stage (with glass support): approx 300 Hz.
- Mass of stage (with glass support): approx 2 gm.
Bimorph Slider (double bimorph type)
- Maximum recommended applied voltage (peak to peak): ±100 V.
- Maximum lateral displacement (at maximum voltage): approx ±50 µm (0.1 mm peak-to-peak).
- Stiffness of bimorphs: approx 104 N/m.
- Resonant frequency of bimorphs and support (stage): approx 200 Hz.
- Mass of support (stage): 8gm.
1 All stainless steel parts of internal surfaces are 316-type non-corrosive, non-magnetic steel. Other internal parts are either silica, PTFE (Teflon) of Kel-F.
2 Much smaller particles trapped between two surfaces can be “detected” due to the much larger deformations they produce on the surrounding surfaces.
3 Values quotes are for semiconductor gauges. Resistance (foil) strain gauges are about 100 times less sensitive (but sturdier and less prone to drift).
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