Plasma Cleaning Process

(Figure 2 2) consists of a foam aqueous electrolyte

that is comprised of at least 30% gas/vapor.   The

The  University  of  New  Orleans,  College  of  Engi 

workpiece is then positioned in a sealed chamber

neering  evaluated  Cathodic  Atmospheric  Plasma

and filled with foam.  A pad of discrete hydrogen

using foam plasma processes for cleaning rust, scale,

bubbles form within the liquid layer on the surface

hydrocarbon, and other forms of contaminants from

of the workpiece.  The conductive path becomes the

conductive  metal  surfaces  allowing  them  to  accept

walls of the foam bubble.  The key to this process is

paint or coatings.  The technology is ready for com 

that  the  distance  between  the  anode  and  the

mercialization, with its first full scale application in

workpiece is less critical than the flow through pro 

the cleaning and preparing of wire, rods, and tubing.

cess.   Tap  water  and  baking  soda  can  be  used  to

create a denser foam material to remove stubborn

The University of New Orleans, College of En 

materials from surfaces.

gineering (UNO COE) is developing and evalu 

UNO COE and its partner, CAP Technologies,

ating electro plasma technology as a source for

LLC, built prototype equipment and evaluated

cleaning and coating metal surfaces for maritime

the cleaning of carbon, stainless, duplex, silicon

applications.  The scope of its work involves the

steels,  copper,  titanium,  and  aluminum.    Zinc,

study  and  comparison  of  flow through  electro 

copper,  lead,  nickel,  copper/nickel,  copper/zinc,

plasma  processes  with  Cathodic  Atmospheric

and  zinc/aluminum  were  deposited  using  the

Plasma (CAP) using foam plasma processes for

process.    Evaluations  of  cleanliness,  corrosion

cleaning  rust,  scale,  hydrocarbon,  and  other

resistance, and adhesion properties were based

forms  of  contaminants  from  conductive  metal

on  data  accumulated  from  polarization  resis 

surfaces allowing them to accept paint or coat 

tance tests, ultraviolet weathering tests, surface

ings.  The technology is ready for transfer to in 

profiling, and others.  Analysis shows that CAP

dustry, with its first full scale application in the

plasma cleaning provides superior cleaning and

cleaning and preparation of wire, rods, and tub 

corrosion  resistance  and  offers  good  adhesion

ing.  The development and evaluation work was

properties at a fraction of the cost of traditional

accomplished in partnership with CAP Technolo 

cleaning and coating methods.  As a result, the

gies, LLC.  Commercialization of the technology

CAP plasma cleaning system is being repackaged

is being pursued to meet the needs in shipbuild 

for use on a production scale to clean metal pipes,

ing and other industrial markets.

rods,  and  tubes  for  sale  to  shipyards  and  com 

Existing processes for removing rust and scales

mercial markets.  Future plans call for broader

from  steel  and  other  conductive  metals  include

commercial applications on metal surfaces and

grit  or  shot  blasting,  acid  pickling,  electrolytic

conductive metal coatings.

cleaning,  electroplating,  and  plasma  processing

in a high vacuum.  UNO

COE s  original  study

evaluated the cost effec 

tiveness, long term per 

formance,  and  environ 

mental considerations of

each  process  compared

to  the  flow through

electro plasma  process.

This  first  generation

technology was soon su 

perceded  by  the  CAP

foam process, which has

fewer critical parameters

and  achieves  more  reli 

able  results  without  the

use of a vacuum system.

The  CAP  foam  process

Figure 2 2.  CAP Foam Process Chamber

8