- Technical Articles & Reports on Plastic Industry

A transparent thin coating or film to be applied on cross linked polystyrene blocks that will be in contact with an aqueous couple gel to improve scratch resistance and surface hardness with the following parameters.

	The coating must be optically transparent or opaque but not coloured, from a acoustic point of view it must be has acoustic impedance confront able with water
	May not change the sound properties of the polymer
	The thickness of the coating must be in the order of 1 micron
	The minimum acceptable hardness value is 55 / 60 HV (HV meaning Hardness in Vickers. It must be emphasized that we made a microhardness test.)
	Shelf life must have a minimum of 2 years

Desired Timeframe : Within 3 months

Field Of Use and Intended Application

	Probes for ultrasonic testing machines
	Quality inspections and controls
	Industrial plants maintenance

Desired Outcome
The coating is required to reduce the wear out of the sound transducer block, improve the quality of the product and it's life cycle and reduce maintenance costs.

Previously Attempted Solutions
We have tried with 3 different nanocoatings that have not satisfied our needs. The problem is that it is difficult to harden the surface of our soft polymer coating it with a nano film and so we need to increase the coating's thickness. We try also with amorphous DLC (1.5 micron thick) and it increases the surface hardness more 60% and so it is a quite good result for us. The problem with amorphous DLC is that it have a high acoustic impedance (because of coating is metallic) and so we had waste it.
Some parameters that can be related to applications:
a) Sound Frequency Band: 1 / 5 MHz
b) Exercise Voltage: 80 V
d) Impulse width: 100.00 ns

(Source Courtsey : Prof D.J.Desai, LD Engg. College)