Atom-sensitive textiles as visual indicators for plasma post-discharges

The efficiency of surface treatments by plasma and post-discharge plasma processes is greatly dependent on the density of active species, such as neutral atoms in post-discharges. Therefore, many diagnostics exist to detect the presence and measure the concentrations of these species, but they often require expensive instrumentation and highly qualified personnel. These conditions are not often met when the process is industrially used and it becomes important to imagine simple indicators allowing to validate that the correct operating conditions are reached. In the present paper, we present the first results on the investigation of an inexpensive and easy to use visual indicator able to quantify the atomic species density in nitrogen post-discharge plasma processes. It is based on the differential recombination coefficients of N-atoms on metallic/textile fibres which are intrinsically bonded together in a fabric matrix which serves as support for a thermochromic ink. The specific heating of the metallic fibres by N-atom recombination heats the whole of the fabric, leading to a visible colour change of the thermochromic ink, and therefore, of the indicator. Through modelling, it was possible to estimate that the inclusion of copper fibres to a pure cotton matrix leads to a 60% increase of the global N-atom recombination coefficient of the fabric, sufficient enough to provide a clearly visible colour change.

[1]  Takuro Yamashita,et al.  Rate of recombination of nitrogen atoms , 1979 .

[2]  A. Ricard,et al.  Determination, through titration with NO, of the concentration of oxygen atoms in the flowing afterglow of Ar-O2 and N2-O2 plasmas used for sterilization purposes , 2001 .

[3]  P. Macko,et al.  Study of oxygen atom recombination on a Pyrex surface at different wall temperatures by means of time-resolved actinometry in a double pulse discharge technique , 2004 .

[4]  T. Belmonte,et al.  Titration of N and C atoms in flowing N2-CH4 post-discharge between 300 K and 850 K , 2004 .

[5]  C. Canal,et al.  Effects of N2 post-discharge plasma treatments on wool fabrics , 2006 .

[6]  A. Ricard,et al.  Density of oxygen atoms in high pressure (10–50 torr) flowing microwave post-discharges for elastomer treatments , 2004 .

[7]  C. Ferreira,et al.  Surface kinetics of N and O atoms in discharges , 1996 .

[8]  R. Young.  Pressure Dependence of the Absolute Catalytic Efficiency of Surfaces for Removal of Atomic Nitrogen , 1961 .

[9]  J. Linnett,et al.  The recombination of oxygen atoms at surfaces , 1958 .

[10]  T. Belmonte,et al.  3D modeling of a microwave post-discharge nitriding reactor , 1997 .

[11]  A. Ricard,et al.  Determination of Nitrogen Atoms Loss Probabilities on Copper, Aluminium, Alumina, Brass and Nylon Surfaces , 2006 .

[12]  G. Cartry,et al.  Atomic oxygen recombination on fused silica: experimental evidence of the surface state influence , 1999 .

[13]  E. Shane,et al.  Nitrogen afterglow and the rate of recombination of nitrogen atoms in the presence of nitrogen, argon, and helium , 1971 .

[14]  M. Pejovic,et al.  Surface recombination of atoms in a nitrogen afterglow , 1994 .

[15]  C. D. Scott.  Effects of nonequilibrium and wall catalysis on Shuttle heat transfer , 1985 .

[16]  Y. C. Kim,et al.  Recombination of oxygen, nitrogen, and hydrogen atoms on silica: kinetics and mechanism , 1991 .

[17]  A. Ricard,et al.  Synergy Between N and O Atom Action and Substrate Surface Temperature in a Sterilization Process Using a Flowing N2‐O2 Microwave Post Discharge , 2005 .

[18]  Ricardo Molina,et al.  Role of the Active Species of Plasmas Involved in the Modification of Textile Materials , 2007 .