Vol.7     No.4       August/September1999                                                                 ISSN:0971-4413
Bulletin of Defence Research & Development Organisation

Products & Processes

pin1.gif (1016 bytes)Directionally Solidified & Single Crystal Turbine Blades & Vanes

A state-of-the-art gas turbine aerofoil component sometimes works in an environment of temperature beyond even the melting point of the alloy used for manufacturing it. These superalloy components possess a complex aerofoil geometry and are investment cast to equiaxed component or columnar grained or single crystal components by directional solidification to increase the performance. The technologies for both equiaxed and columnar grains or single crystal have been indigenously developed and demonstrated by DRDO for a variety of components. In the directional solidification, a bottom open ceramic shell mould is placed on a water cooled copper plate mounted on a ram shaft and is heated by an in situ mould heater in a vacuum casting furnace to a temperature beyond the melting point of the alloy to be cast. When the melted alloy is poured into the mould the alloy at the copper plate gets chilled and a columnar grained structure develops in the direction of heat extraction. The solidification proceeds into the mould cavity when the mould is lowered out of the mould heater. To produce a single crystal structure, some constriction ahead of initial columnar grain structure that allows growth of only one of the grains of the columnar structure, usually a helix with about one turn, is used.

Leachable fused silica cores are used for casting aerofoils to very tight tolerances with complex internal cooling passages characterised by thin walls of the order of 0.5 mm. The shell and core system is designed so that no distortion occurs at the temperature of directional solidification of about 1500 oC.

pin1.gif (1016 bytes)Brake Piston Insulator for LCA

Brake piston insulatorBrake Piston Insulator is a critical component in the wheel assembly of the Light Combat Aircraft (LCA) currently under advance stage of development. The insulator pads are mounted on brake piston for restricting temperature rise of hydraulic oil during brake application. The insulator pads therefore not only face compressive stresses but are also subjected to high temperature as a result of conversion of kinetic energy into heat energy during application of brakes.

An import substitute for brake piston insulator has been successfully developed by DRDO. The material has matrix of stainless steel with dispersion of SiO2 particles and feldspar as the binding phase to provide thermal insulation property. This material was produced by powder metallurgy route and subsequently tested for crushing strength, load bearing capacity, hardness, etc. Insulators, manufactured from the above material, were tested along with wheel and carbon brake assembly on brake dynamometer facilities at Hindustan Aeronautics Limited. As a part of full qualification test requirement, the wheel and carbon brake assembly have been subjected to rejected take off energy conditions.

pin1.gif (1016 bytes)Composite Laminate for LCA Windshield

A four-ply composite laminate, consisting of two exterior cast acrylic sheets of 3 mm and 2.5 mm thickness and two interior polycarbonate sheets each of 6.4 mm thickness, has been developed by DRDO for application in fabrication of windshield for LCA. All the four structural plies are bonded together with three inter-layers of clear transparent non-yellowing polyurethane adhesive film. One millimeter thick adhesive inter-layer between the plies is used to provide smooth curvature to windshield contour. The adhesive layer provides good bond adhesion between the structural plies, impact resistance and energy absorption against bird strike besides accommodating differential thermal expansion/contraction of structural plies.

The air-bubble free composite laminate windshield provides optically clear, distortion-free visibility along with protection against bird hit.

pin1.gif (1016 bytes)Fuel Cell

A one kilowatt phosphoric acid fuel cell based on state-of-the-art catalyst impregnated electrodes, high strength carbon plates for gas manifolds, and high performance sealants has been designed and developed by the DRDO.

The cell use hydrogen as fuel. A methanol reformer has also been developed for continuous generation of hydrogen. The prototype fuel cell has been fabricated and integrated with methanol reformer. The cell has been fully tested and technology has been demonstrated. Possible applications of fuel cell include, submersibles, vehicles, remote area power stations, etc.

pin1.gif (1016 bytes)Titanium Sponge

India has world’s largest reserves of titanium ores.Titanium sponge cake Bulk of the ore in the country is converted into pigment grade titanium dioxide through an intermeDIATe product titanium tetrachloride. A commercial plant for conversion of imported titanium sponge metal into finished mill product through melting, forging, rolling, etc., is also available in the country. The only technology gap that exists is for the conversion of titanium tetrachloride into titanium sponge metal. There is an urgent need for commercialisation of titanium in the country so that the vast resources available in the country can be gainfully utilised for variety of applications in defence, aerospace, oil and power sector industries.

DRDO has developed a technology to convert TiCl4 into titanium sponge up to a batch size of 4 tons using magnesium reduction process. Technology is proven in the laboratory and being ruggedised for production.

pin1.gif (1016 bytes)Titanium Tube Drain Cooler

Lubricate oil drain cooler-cum-heat exchanger has been developed using indigenously produced titanium tubes and plates. This heat exchanger will replace the currently used cupro-nickel tube heat exchanger in naval ships.

User evaluation trials have been successfully carried out on a naval ship and it has been accepted for introduction into the Services.

Main Characteristics
  • High corrosion and erosion resistance

  • Better shock resistance

  • High strength to weight ratio

  • High thermal efficiency and toughness.


pin1.gif (1016 bytes)Polymeric Dock Blocks

Polymeric dock blocks, based on blend of rubber and special plastics, have been developed for centre line docking of ships as an alternative to expensive teak wood block currently in use. The blocks have superior load carrying capacity, structural integrity, and are more durable than wood. Extensive user trials are in progress.

pin1.gif (1016 bytes)Helmet Combat Fibre Glass

DRDO has developed a Helmet Combat FibreHelmet combat fibre glass Glass for use by soldiers to provide protection against high velocity fragments and low velocity small arms bullets. The shell body of the helmet is made of glass reinforced plastic using ‘E’ glass woven roving fabrics and unsaturated polyester resin and shaped by matched metal die moulding process. Inner harness consists of cradle suspension, back headrest, chin strap with velcro fastener. All harness are made from tape cotton special. Synthetic rubber beading is provided to protect peripheral edges against damage due to abrasion.

The helmet has been developed in two shades, viz., olive-green and sand colour. The finished helmet weighs 1.1 kg. The helmet is currently being used by the Services, paramilitary forces and police of various states.

Main Characteristics

  • Helmet provisioned in one universal size to suit all head sizes by adjustment of head-band and chin strap

  • Easy-to-handle and comfortable for use in extreme climatic conditions

  • Withstands 0.38 pistol bullet strike from point blank range (6 m distance).


pin[1].gif (1016 bytes)Radar Scattering Camouflage Net

DRDO has developed an indigenous synthetic pre-garnished Radar Scattering Camouflage Net (RSCN) to provide protection to ground-based military objects against modern reconnaissance systems. It consists of a well designed garnishing material developed from PVC coated nylon fabric having a suitable metallised polyester grid structure. Suitable pigments were used in PVC coating to provide desired visual and near IR reflectance.

The coated fabric was incised in a definite pattern for adaptability to natural back ground and mounted on flexible strong synthetic net frame. The RSCN has been recommended for introduction into the Services.


        Main Characteristics

           Pre-garnished and provided with  camouflage pattern suitable for green belt      and desert terrains

    Possesses camouflage properties at visible, near infrared and microwave frequencies

    Does not propagate flame in case of fire

    Low water absorption

    Indigenously available raw materials.

pin1.gif (1016 bytes)New Fire Extinguishing Composition

The current protocol on ozone depleting substances requires gradual phasing out of Chloro-Fluoro-Carbon (CFC) and halons. DRDO has developed a dry chemical powder based on mono-ammonium phosphate (MAP) to replace Halon 1211 as a fire extinguishant in non-critical defence applications. Extensive field trials with indigenously developed formulations have shown exceptional fire extinguishing efficiency to fight A, B and C classes of fires. The critical processing parameters like siliconising treatment of MAP, curing, etc., have been optimised for all the production steps. Process has been up-scaled to 10 kg batch in the laboratory and is ready for transfer of technology.

The powder meets all the essential parameters, i.e., high fluidity, humidity resistance, etc. as per national and international specifications. The resulted development will drastically reduce the cost of investment, inventory control and maintenance.

pin[1].gif (1016 bytes)Gun Recoil Fluid

DRDO has developed a siloxane-based indigenous gun recoil fluid to meet the critical requirements of the Army. It is based on neutral, low viscosity, fully endcapped polydimethyl siloxane fluid with a low coefficient of volumetric expansion. The fluid fully meets the required specifications. The recoil fluid can also be used as a coolant and working fluid, besides its use as an additive in polishing compounds.

Main Characteristics

  • Low pour and freezing point (< -50 oC)

  • High flash point

  • Anticorrosive towards mild steel, cast iron, stainless steel, copper, brass, and chrome plated steel

  • Compatible with various types of synthetic rubbers

  • Operating temperature: - 50 oC to 150oC.

pin1.gif (1016 bytes)Cellulose Membrane as Selective Pervaporation Barrier

The bacterial membrane is one of the most pure forms of cellulose. DRDO has developed a special process to obtain cellulose membrane from a bacterium. The membrane is produced in the form of very thin (0.05 to 0.08 mm) sheet by using special chemicals and was modified using a special technique.

The membrane has immense potential because of its use in wound dressing, for tissue transplantation in case of severe burns, and as an acoustic diaphragm. Cellulose membrane is specifically useful for concentrating chemicals prone to thermal degradation. At present pervaporation membranes are mostly made from synthetic material and this membrane may prove to be more cost effective.

pin1.gif (1016 bytes)Jackal Armour for Bullet Proof Jacket & Vehicles

Tfa10.tif (514853 bytes)Jackal armour steel technology has been developed by DRDO for infantry combat vehicles and light-weight bullet proof jackets by optimisation of chemical composition and several manufacturing parameters, such as primary melting, forging, hot rolling, cold rolling, annealing, shearing, grinding, forming, heat treatment, shot blasting and finally microstructure and mechanical properties.

The Jackal armour steel technology for bullet stopping harness has been transferred to Mishra Dhatu Nigam (MIDHANI), Hyderabad, while the technology for steel, designated as Jackal M1, has been transferred to Steel Authority of India Ltd. (SAIL) for armour plate production. A large number of sets have already been supplied for actual use.

Jackal is also being used for variety of other applications, such as BMP I, mobile launcher for missiles and internal security vehicles.

pin1.gif (1016 bytes)Antispark Tools

DRDO has indegenously developed Antispark toolsa variety of copper-based antispark tools to meet the requirements in Defence as well as civil sector. At present, the alloy, based on the Cu-Be system, is produced by Bhabha Atomic Research Centre, Mumbai and processed into sheets and strips by DRDO. This alloy can be used to make springs, diaphragms, bellows, connectors, electronic and electric contacts, bearing cams, spark-less tools, resistance welding electrodes, and non-magnetic related tools.

More recently, Cu-Ti alloys have been developed with similar anti-sparking properties, replacing the difficult to process Cu-Be alloys.

pin1.gif (1016 bytes)Aluminium Alloy Cast Components for Torpedoes

Tfa8.tif (496071 bytes)Aluminium alloy     cast components form a part of  main torpedo structure. Complex geometry and stringent specifications of the components makes it a challenging task. The complete development plan includes casting design, method, pattern development, melting and casting, fettling, proof machining, heat treatment, NDT and mechanical testing, macro/microstructure evaluation, final machining and anodising, leak testing and hydraulic pressure testing.

DRDO has developed and produced four aluminium alloy cast components, viz, shell warhead, shell housing, front cover, and rear cover for the torpedoes.

These components are developed for the first time in India and meet all user requirements.

pin1.gif (1016 bytes)Steel for Structural & Armour Application

Two grades of ultra clean structural and armour steel of HSLA variety, e.g., copper-brown (CuBx) and Armour (ARX) have been designed and developed for structural and armour applications respectively.

The CuBx and ARX have been produced on pilot scale in as rolled condition following thermo mechanical processing route and have been characterised in respect of chemistry, microstructure, mechanical and impact properties. The CuBx steel hold high promise as a high strength ultra high toughness steel for structural applications. About 20 ton of CuBx steel has been made in collaboration with ASP, Durgapur.

The noteworthy feature of CuBx and ARX steels are excellent mechanical properties, such as charpy energy and better yield strength.

pin1.gif (1016 bytes)Rare Earth Permanent Magnets

Permament magnet materialDRDO has developed Rare Earth permanent magnets (SmCo5 and Nd2Fe14B) of various shapes and sizes. These magnets possess excellent combination of magnetic properties, such as coercivity, remnance and energy product, and allow device miniaturisation. TFA3.tif (1971589 bytes)

Rare Earth permanent magnets are used in variety of sensors, stepper motors, and other electro-mechanical appliances needed for Defence, Aerospace and Civilian Industries.

pin1.gif (1016 bytes)Advanced Ultra High Strength Steel

Steel for use in aerospace should possess ultra high strength coupled with high fracture toughness in order to meet the requirement of minimum weight while ensuring high reliability. The commercial use of low-alloy steels for such applications has often been limited by their low combination of strength and fracture toughness. DRDO has developed an ultra high strength, high fracture toughness, NiSiCrCoMo low alloy steel, designated as DMR-S1700.

Tfa7.tif (1422693 bytes)The strength-toughness properties of DMR-S1700 approach the properties of 250 grade maraging steel. Reproducibility of attractive strength and toughness properties of DMR-S1700 has been established in tonnage scale melts. This steel, in the softened condition, has good formability and machinability. Weld parameters have also been established. The DMR-S1700 meets the requirements of performance and cost (one-third of that of 250 grade maraging steel) rendering it an attractive substitute for expensive high alloy maraging steel, weight in high performance structural applications such as booster motor castings.

This advanced steel can have many other applications, as in the base plate of mortars. Such components have undergone trials. The weight of these components could be reduced by 34 per cent as compared to STA 59 steel which is currently being used.

pin1.gif (1016 bytes)Indigenous Glucose Analogue

2-Deoxy-D-glucose (2-DG) is a glucose analogue extensively used as a tool to study the glucose transport and regulation of glucose metabolism in a variety of cellular systems and intact organisms including primates and humans. 2-DG has also been extensively used in patients suffering from different tumors, gastric ulcer, to test for completeness of vagotomy, and also for differential diagnosis of hypoglycemia in children without any untoward side effects.

DRDO has developed the technology for the preparation of 2-DG using indigenously available chemicals. The toxicological and efficacy studies have been carried out on different strains of rats and were found to be at par or even superior than the imported product.

pin1.gif (1016 bytes)Radiopharmaceutical for an early in vivo Localisation of       Skeletons

In the field of radiopharmaceuticals with wide applications in the area of nuclear medicine and magnetic resonance imaging, a new radiopharmaceutical has been developed by the DRDO. This pharmaceutical, Bz-EDTMPA, is useful for an early imaging of bone metastasis and will be applicable for the palliation of pain associated with metastatic bone cancer using appropriate b-emitting radionuclide.

The pharmaceutical is bi-functional in nature that makes it specific for targeted diagnosis and therapy by coupling with biologically active molecules. It can be labeled with several different radioisotope at a time while many conventional radiopharmaceutical can not be labeled with available radionuclide in India, such as I-131, which is b-emitting radioisotope widely used for therapeutic application. At present, the pharmaceutical is undergoing multicentric trials at different centres of nuclear medicine in India. A patent has been filed for the preparation process of the new pharmaceutical.

pin1.gif (1016 bytes)New Chelating Agent

Monoisoamyl dimercapto-succinic acid (MiADMSA) is a newly developed chelating agent for the treatment of gallium-arsenide poisoning. MiADMSA is an analogue of meso 2, 3-dimercaptosuccinic acid, an orally effective drug for the treatment of childhood lead poisoning. MiADMSA has been proved highly effective in removing arsenic from gallium-arsenide exposed experimental animals and recoveries in the altered biochemical variables. While the therapeutic efficacy of MiADMSA has been proved against gallium-arsenide experimentally, efforts are on to determine its efficacy against acute and chronic arsenic poisoning. The drug may be of potential use to people suffering from arsenicosis.

pin1.gif (1016 bytes)Fluoroacetamide–A single dose rodenticide

Various methods have been used for the control of communal rodents, but rodenticides have been found as the best weapon for rodent control. Rodenticides are mainly classified into two groups: single dose rodenticide and multiple dose rodenticides. Both the groups have their own merits and demerits. Single dose rodenticide is quick acting but causes bait shyness which can be overcome by pre-baiting, while multiple dose rodenticide poses problems of resistance among rats.

DRDO has developed a process for the preparation of a single dose rodenticide—fluoroacetamide—which has been found very effective against rats. Fluoroacetamide has been included in the schedule of Central Insecticide Board for commercial viability in the country. However, keeping its toxicity in view, it is recommended for controlled use under supervision.

A patent for preparation process of fluoroacetamide has been filed and the technology is being transferred to prospective entrepreneurs.

pin1.gif (1016 bytes)Intumescent Fire Retardant Paint

An intumescent fire retardant paint has been developed by DRDO to offer intumescent fire retardant characteristics to surfaces like wood, metal, PVC, etc. The paint is based on commercial polymer, high char materials and blowing agent, and imparts satisfactory intumescent characteristics to the substrate when exposed to flame temperature of 1400 oC for a period of 10-15 minutes. When burned, the paint does not emit toxic fumes and also provides adequate thermal insulation to the surface. Technical trial carried out so far has shown that plywood models of huts and PVC cables are completely protected by this paint from intense fire at a temperature of 950 oC for 10-15 minutes. User evaluation trials are in progress.

pin1.gif (1016 bytes)High Performance Exterior Paint

A high performance exterior paint has been developed by DRDO to offer long term chalking free and glossy surfaces to exterior superstructures of ships. The paint is based on silicon modified soys alkyd and acrylated resins. The paint has superior resistance, more than 30 months, to chalking and superior gloss retention than conventional paints.

Successful user trials have been carried out on naval ships.

pin1.gif (1016 bytes)Heavy Duty Non-Skid Paint

A heavy duty non-skid paint has been developed by DRDO to provide non-skid surface for flight deck of aircraft carriers and helicopter deck of ships. The paint is based on epoxy resin/coarse conglomerates and has a very high frictional coefficient, resistance to weathering and thermal cycles. The service life of the paint is 4-5 years and is capable of withstanding 5000 landings of aircraft. The paint has been accepted for use by the Indian Navy and the technology has been transferred for commercial production.

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Materials/ Products& Processes/ Technology