Spiral Contractometer Instructions For Nickel Deposit Stress

Step 1: Place the anode basket containing nickel anode buttons in a 4,000 ml Pyrex beaker, then place the beaker over a magnetic stirrer hot plate, add the desired plating solution to the beaker, then place the spiral contractometer adjustable support stand over the beaker and anode basket and warm the plating solution to the desired temperature.

Step 2: If a nickel strike is necessary for adhesion of the applied coating, pour the nickel strike solution into a beaker (approx. 9.5″) use a circular titanium anode basket containing nickel anodes or buttons.

Step 3: Clean a spiral (helix) as the cathode (positive charge) in an alkaline steel electrocleaner at 3 amps for 30 seconds and water rinse.

Step 4: Nickel strike the spiral (helix) at 3 amps for 1 minute. Remove the spiral (helix) from the spiral contractometer and water rinse, isopropyl alcohol rinse and dry.

Step 5: Weigh the spiral (helix) to the nearest milligram and record the weight in grams. Note: use gloves to prevent contamination of the spiral (helix).

Step 6: Mount the spiral (helix) onto the spiral contractometer and tighten the Polycarbonate screws through the holes provided sufficiently to secure the spiral (helix) so as to prevent slippage during the plating process. Note: the wire contact end must be positioned over the top of the spiral (helix) with the screw provided.

Step 7: Place the spiral (helix) contractometer assembly and the attached spiral (helix) into the adjustable support stand holes located on the top surface of the stand. Then allow two minutes for the spiral (helix) to reach the plating bath temperature.

Step 1: Loosen the pulley wheel screw that holds the pulley wheel tight against the top of the center rod and position the dial by rotating it to match the zero with the arrow, then tighten the screw to secure the rod so slippage cannot occur during the plating cycle.

Note: It is important that when the spiral (helix) is attached to the contractometer, a space of about 3/16 inch should be allowed between the bottom of the contractometer spiral shaft and the top of the spiral (helix) holder knob at the bottom where the spiral (helix) is attached.

Step 2: Place the eye loop thread of one of the calibration weight string over the pulley calibration pin at the zero and wrap the thread clockwise part way around the pulley calibration wheel, then suspend the thread and weight over the grooved guide wheel near the Kc marker.

Step 3: Place the eye loop thread of second calibration weight string over the remaining pulley calibration pin and wrap the thread clockwise part way around the pulley calibration wheel, then suspend the weight over the grooved guide wheel near the Kc marker.

Step 4: Tap the pulley calibration wheel at the top center of the contractometer lightly and read the degrees compressive stress. Record this degree reading as Kc. Note: The compressive stress values are identified with a minus sign.

Step 5: Remove the eye loop threads from the pins and repeat the above procedure except for wrapping the strings counterclockwise and suspending the threads over the grooved guide wheels near the Kt markers. Again, tap the pulley calibration wheel at the top center of the contractometer lightly and read the degrees tensile stress. Record this reading as Kt. Finally, remove the eye loop calibration string and weights.

Step 1: Make sure the solution temperature is the desired temperature within ± 3°F.

Step 2: Set the timer for the desired plating time.

Step 3: Connect the positive lead (usually red) of the power supply to the anode basket and the remaining lead (usually black) to the metal contact at the top of the spiral contractometer.

Step 4: With the rectifier plugged into the timer, turn on the timer and begin the plating process. For critical work, maintain the bath temperature within ± 3°F. It is helpful to tap the top of the pulley calibration wheel every 3 minutes or so with a blunt instrument to assist in stabilizing the degree reading.

Step 5: When the plating time expires, tap lightly on the top of the pulley calibration wheel to stabilize the degree value, then read the final degrees value and note if the stress is compressive (negative) or tensile (positive). Record the degree value as Kc- or Kt+ accordingly.

Step 6: Remove the spiral contractometer from the adjustable support stand, rinse the spiral (helix) in water, and rinse it in 70 % isopropyl alcohol. Remove the spiral (helix) from the contractometer using gloves. Dry thoroughly. Note: It is helpful to pull part of a rolled sheet of paper towel gently through the interior of the spiral (helix) to assist in drying.

Step 7: When the spiral (helix) is completely dry, weigh the spiral (helix) and record the weight in grams.

Step 1: Plated spirals (helices) can be stripped of nickel deposits repeatedly in a 50% by volume nitric acid solution for reuse. Do not heat the solution above 90°F.

Step 2: When the exterior surface of a Spiral (helix) shows visible etching, the helix should be discarded.