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

SMART TEXTILES (Introduction)

• Smart textiles are the textiles which sense and react to environment conditions or stimuli.

• Smart textiles are able to sense changes in their environment and can act upon predetermined ways.

• They work on three basic parts :- Sensors, Actuators and Units (Systems)

Sensors 

Sensor is a device that detects or responds to a physical or chemical change.

Actuators

Actuator converts energy into motion, releases substance, noise and many other ways.

• Smart textiles are classified in three categories:-

  

• 1. Passive Smart Textiles (Sensors):- They can only sense the environment conditions.

  Examples:- Optic fibre, Conductive Material, Thermocouple

  2. Active Smart Textile (Sensors & Actuators):- They can sense and react to the environment conditions.

  Examples:- 

  Type – I :- Chromatic materials, Shape Memory materials, Phase Change materials,   

                     Hydrogel and Membranes

  Type – II :- Luminescent materials, Photovoltaic, Electric textiles

  3. Very Smart Textiles (Units and Systems):- They can sense, react and adapt themselves accordingly.

  Examples:- Space suits, Thermo regulating clothing, Health monitoring apparel

  Types of Sensors:- 

  • Blood Pressure Measuring Sensor

  • Body Temperature Measuring Sensor 

  • Positive Temperature Coefficient (PTC)

  • Negative Temperature Coefficient (NTC)

  • Pulse Rate Measuring Sensor

  Materials used for Smart Textiles

  • Metal fibres

  • Conductive inks

  • Inherently conductive polymer

  • Optical fibre

  • Coating with nanoparticles

  • Organic semiconductor

  • Shape memory materials

  • Chromic materials

  Application of Smart Textiles

  • Health care

  • Life belt

  • Life jacket

  • Defence

  • Fashion and entertainment

  • Sports wear

  • Purpose clothing

  • Transport and automotive use

  
  

  Phase Change Material (PCM)

  It is a latent heat storage material, which can be integrated into textile structures, in numerous ways, as microcapsules.

  Examples:- Paraffin wax, Fatty acid, Hydrated solutions, Eutectics or organic and inorganic compound.

PROTECTIVE TEXTILES (Introduction)

• The clothing itself provides the protection rather than an individual textile material, but textile fabric is the critical element in all protective clothing and other protective textile products.
• As the safety barrier between the wearer and the source of potential injury, it is the characteristics of the fabric that will determine the degree of injury suffered by the victim of an accident.
• There has been a large increase in the hazards to which humans are exposed as a result of developments in technology in the workplace and on the battlefield, for example.
• The need to protect against these agencies is paralleled by the desire to increase protection against natural forces and elements.
• The dangers are often so specialized that no single type of clothing will be adequate for work outside the normal routine.

In order to be successful, designers need to work closely with quality assurance and production personnel as well as potential customers and users from the earliest stages of development.

The types of protective garments specifically mentioned in the literature are :

• Tents
• Helmets
• Gloves (for hand and arm protection)
• Sleeping bags
• Survival bags and suits
• Fire-protective clothing
• Heat-resistant garments
• Turnout coats
• Ballistic-resistant vents
• Biological and chemical protective clothing
• Blast-proof vests
• Antiflash hoods and gloves
• Molten metal protective clothing
• Flotation vests
• Military protective apparel Including  antihypothermia suits and ducted warm air garments
• Submarine survival suits
• Immersion suits and dive skins
• Life rafts
• Diapers
• Antiexposure overalls
• Arctic survival suits
• Ropes and harnesses

The types of occupation and activities for which protective garments and other products are made specifically mentioned in the literature are :

• Police
• Security guards
• Mountaineering
• Caving
• Skiing
• Aircrew (both military and civil)
• Soldiers
• Sailors
• Submariners
• Foundry and glass workers
• Firefighters
• Water sports
• Winter sports
• Commercial finishing and diving
• Offshore oil and gas rig workers
• Healthcare
• Racing drivers
• Astronauts
• Coal mining
• Cold store workers

Types of Protection

·         Flame retardant

o   Kermel® and Kermel® / Viscose fabrics for flight suits, station wear and turnout gear.

o   Nomex® for military applications

o   Molten Aluminum splash protective fabric.

o   Electrical Arc

·         Ballistic protection

o   p – Aramid woven fabric for hard and soft ballistic applications

·         Lint free antistatic

o   Continuous filament polyester / carbon fabrics

·         Medical textiles

o   Systemic and non-systemic antibacterial and antistatic fabrics for surgeons gowns, scrubs and warm up jackets.

·         Chemical protection

o   Liquid chemical protective fabrics

·         UV protection

o   Fabrics that offer a UPF rating for the wearer.

·         Industrial work wear

o   Component fabrics for chain saw protection

o   freezer suits

o   waterproof clothing

·         Military textiles

o   Uniforms

o   Parachutes

Classifications of Protective Textiles

Ø  Materials & Technologies

·         Processing technologies for specific protective clothing are different, the main processes generally include:

1.      Material manufacturing or selection;

2.      Producing fabrics and other related items;

3.      Finishing, and

4.      Clothing engineering.