Calculations for Optimizing Surface Oxide Testing Systems.

Current Density Determination:

G. Baker

March 13, 2008



Practical Strategies For Reducing Current Density:

The overall concept is to reduce current density as much as possible given the time available. For example, let�s say a plant produces a rod coil every 14 minutes when running consistency. Furthermore, let�s say that the lab manager desires that each surface oxide test definitely completes within 12 minutes. The simplest step is to set the current density such that a sample with the highest possible oxide measurement would complete at exactly 12 minutes. This is not a simple calculation since various constituents require different times to reduce per their thickness.



To reduce the current density further one or more of the following techniques can be employed:



Set a Time Limit:

Instead of setting the highest possible oxide measurement to complete in 12 minutes, set the highest possible oxide measurement that is not downgraded to complete in 12 minutes. With this method, any test that is not complete within the maximum time will be automatically downgraded. For surface oxide software, which does not provide this capability, an automated external timer can be connected to the circuitry or the lab technicians can simply note if the test has exceeded the maximum time and prematurely stop the test. The disadvantage to this current density reduction method is a complete knowledge of those long test results are lost.



Download this Excel file to make these estimations.


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