CERAMIC FIBER

            Inorganic fibers are attractive because of their resistance to combustion and their high thermal stability relative to organic fibers. The base material of ceramic fiber textile products consists of ceramic staple fiber yarns containing ceramic fiber and small quantity of organic fiber that decomposes from about 200°C. These yarns are reinforced either with steel wires (for 1100°C) or glass filaments (for 650°C) in order to ensure that the mechanical strength is maintained up to the high temperatures.

 

Basic Composition of Ceramic Fiber:-

SiO₂                             :           50 – 60 %

Al₂O₃                           :           30 – 50 %

Na₂O.H₂O                   :           0.1 %

Fe₂O₃                           :           0.04 %

Leachable Chlorides   :           10 ppm

 

Multifilament Ceramic Fibers (˃ 20 μm diameter)

Type	Name		Tensile Strength (Gpa)	Modulus (Gpa)	Exp. (%)	Density (g/cm3)
Silicon Carbide	Nicalon	12% O	3.0	180	1.5	2.5
	Tyranno	12% O; 11% T	2.8	210	1.5	2.4
Silicon Nitride	Tonen	4% O	2.5	300	---	2.5
Silicon Carbonitride	Fibreamic	23% N; 12% C; 4% O	1.8	220	0.9	2.4
Alumina / Silica	Nextel 312	24% SiO2; 14% B2O3	1.7	154	---	2.7
	Nextel 480	28% SiO2; 2% B2O3	2.3	224	---	3.0
	Altex	15% SiO2	2.0	230	0.8	3.2
α-Alumina	Fiber FP	[α-Al2O3]	1.4	380	0.4	3.9
	PRD – 166	15% ZrO2	1.9	380	0.6	4.2

Ceramic Fibers Properties

ð  Colour                                     :           White

ð  Fiber Diameter                        :           2 – 3 micron

ð  Specific Heat                           :           1130 J/Kg°C

ð  Fire Reaction                           :           Incombustible

ð  Resistance to Chemical agents:           Good

ð  Continuous use limit               :           1260 °C

ð  Melting Point                          :           1790 °C

ð  Excellent thermal shock resistance

ð  Good dimensional stability

ð  Low thermal conductivity

ð  Maximum temperature            :           Reinforced glass : 650 °C

                                                                  Reinforced steel wire : 1100 °C

Process Control in Jigger Dyeing Machine

 

Parameter	Check point	Method of Checking	Standard/ Frequency of check	Necessary Action(s)
Fabric preparation	Prior to dyeing	pH of the cloth Uniform whiteness Absorbency Selvedge crease/ Body creases	Near Neutral Uniform whiteness Good Absorbency No creases/ Each bleach lot	Ensure good fabric preparation
Batching	During Batching	Visual	Random check	Knife edge batching Ensure no slippage Proper working of expander Uniform tension at the time batching
Batch Size	During batching	Measurement of yardage	Maximum permissible load Random check	Ensure that jigger is not overloaded
MLR	Prior/During Dyeing	Check for water level Check for weight of fabric load	Once a shift	Maintain constant MLR Prevent water leakages
Selection of end cloth	Prior to dyeing	Length and colour of end cloth Compatible with the shade	Random check	Ensure proper selection and length of end cloth
Crease-free working of jiggers	During dyeing	Visual	During each round	Adjust alignment expanders Adjust roller alignment Remove crease manually, if possible
Recipe	Prior dyeing	Scrutinizing of chemical slip should compatible with shade	Once a day	Take corrective measure
Colour Preparation	During Colour preparation	Visual/Spotting on filter paper	Random check	Ensure proper dissolution of dye Strain of the dye Investigation method of dissolution Ensure proper vatting of vat dye
Colour/Chemical Addition	During Dyeing	Visual   Vat yellow/ Congo red Paper   Phenolphthalein paper	Random  check	Carry out colour addition in equal parts Effect proper stirring of colour Predissolve all solid chemicals and add
Concentration of chemicals	During dyeing	Titration	During round	Ensure proper concentration
Temperature	During dyeing	Thermometer Thermocouple Thermistor All of the above	During each round	Regulate steam supply Carry out heating at the end of turn Prefer thermocouple
pH	During dyeing	pH paper Direct – 10.4 Reactive – 11.2 Vat – 11.4	As per the class of dyestuffs	Take corrective measure Give adequate time/ number of ends
Time	During dyeing	Time record, number of ends	As per the class of dyestuffs	Take corrective measure Give adequate time/ number of ends
Correction of shade	During process	Visual	Whenever Possible	Maintain the MLR Add extra colour
After treatment	After dyeing	Laboratory analysis	As per class of dyes	Direct – dye fixing treatment Azoic – thorough soaping with dispersing agent Reactive – (NID) soaping for preventing the tinting Disperse – reduction clearing treatment
Redyeing	During Process	Production record	Minimum redyeing	Investigate the reason of for redyeing

 

Reference: Orientation Programme in Wet Processing (Quality and Process Control) organised by BTRA, Mumbai