ROMNET-ERA Network:

“Multifunctional materials and new production processes”

Network partners and their offer in the NMP field -
KNOWLEDGE-BASED MULTIFUNCTIONAL MATERIALS and NEW PRODUCTION PROCESSES AND DEVICES

 

 

National Institute for Aerospace Researches “Elie Carafoli” – INCAS

INCAS Offer

- Interest in FP 6 call: 'Nanotechnologies and nanosciences, knowledge-based multifunctional materials and new production processes and devices ‘ -FP6-2004-NMP-TI-4

- Proposals thin films and C-C nanocomposites INCAS

Name of the Network: Multifunctional materials and new production processes

Contact person, scientific title : Victor Manoliu, Dr. Eng.
Department : Materials and Tribology Department
Organisation’s address : 220, Iuliu Maniu, Sector 6
Post code : 061126
City : Bucharest
Country : Romania
Organisation type
: Research
Organisation size : 150 employees
Web site : www.incas.ro
E-mail address : [email protected]
Telephone : 004021.434.01.53
Fax : 004021.434.00.82

Brief description of the organisation: The institute was established in 1948 as a main department of Institute for Applied Mechanics. Since the time of its foundation the institute has been concerned with problems of aircraft engineering, aeronautical technology and highly advanced research activities. Our mine line of business is research of fluid mechanics and flight dynamics, experimental aerodynamics, tribology, materials and engineering assistance to industry. The entire scientific and technical research of our institute is based on the following principles: enlargement of scope from fundamental research to applied research, interest for traditional theme and new developments, developing and strengthening cooperation. The institute is subdivide into the following laboratories and group: the experimental aerodynamics laboratories (The Trisonc Wind Tunnel, The Ludwin and Shocks Tubes, The Subsonic Wind Tunnel), the theoretical aerodynamic group, the flying dynamic group, the model design group, the mechano-hidro-pneumatic group, industrial aerodynamics laboratory, system analysis laboratory, tribology and materials laboratory, quality assurance, special applications.

Brief description of involved Department: The Laboratory assures in principal the quality system for civil and military aeronautical industry and function in the following researches directions: coatings - thermal barrier coatings (TBC), erosive, abrasive, corrosive wear stressed coatings (ceramic, vitro ceramic-enamels); tribology - lubrication, friction and wear of friction and antifriction materials, hydrodynamic calculation of sliding bearings, liquid and solid lubricants, greases, rheology of multi grade oils, antifriction materials bearings design, sliding bearings manufacturing, mechanical seals, design of special bearings using non – conventional technologies, tribological researches and tests for materials optimization, parts geometry and severe loaded mechanical subassembly; composites - carbon fiber, carbon fiber composites, C-C composites; investigation - structural analysis (SEM, TEM, EDX); multifunctional materials - p lasma processing, multifunctional ceramic thin films with radically new proprieties, nanocomposites epoxy – Montmorillonite, carbon – carbon composites nano-ceramic matrix.

Thin films

3.4.2.2. Technologies associated with the production, transformation

and processing of knowledge-based multifunctional materials

3.4.2.2.1. Advanced materials processing

Plasma processing

The fundamental characteristics of plasma process are represented by the assured flame temperature, about 1500 Celsius degrees, jet speed about 300 m/s, layer porosity about 2%. The main parameters of the plasma process are sketched as follows:

  • Plasma parameters:
  • Air dilution
  • Gas composition
  • Plasma jet temperature
  • Speed
  • Flame:
  • Flame speed
  • Spraying distance
  • Nozzle:
  • Flow gas
  • Powder flow
  • Powder:
  • Distribution,size, grain shape
  • Spray speed distribution
  • Staying time in plasma
  • Under layer
  • Temperature
  • Residual tension control
  • Particle impact speed

 

The process limits are specially determined by the reduced adherence between metal support and bonding layers, high porosity and partial oxidation of the particles.

Fundamental problems to be solved in our opinion by the research in the field are represents by the:

  • Plasma generator power increase;
  • Powder flow speed increase ;
  • Comparable study of the condition by air pressure environment about layers porosity, structure modification , deposition part;
  • Realisation for management of the technological process, especial for ceramic layers of a relax structure with deliberate accomplished porosity and micro cracks;
  • Computerised metallography and electronic microscopy investigations regarding the interface aspects, support - adherence layer - external layers and dynamic of the modifications induced by diferent mechanic and thermal stresses .

Within the consortium, in connection with this theme, INCAS is able to participate in the activities associated to the last two paragraphs

3.4.2.2.3. Multifunctional ceramic thin films with radically new proprieties Multifunctional ceramic thin films

INCAS have the experience to achieve some duplex, triplex layers, FGM - functionally graded materials, ceramics for industrial proposed especial for “hot parts” of turbojet, for some metallurgy parts, power industry, etc.

The aimed parts are stressed at erosive, corrosive wear, thermal shock, sliding friction, which can work simultaneously at high values.

The ceramic layers unanimous utilized, generally partial stabilized zirconia base, have as main servitude, the major difference between thermal expansion coefficients values of ceramic layers and metallic support during thermal shock and associated induced internal stressed.

To decrease the thermal shock effect on the ceramic layers, multilayered structures, FGM, etc. are utilized. Each intermediate layer composition is graded between external layers (internal and external). A progress in this domain, is represented by the recent experimental studies performed by Lewis Research Center, Cleveland, Ohio, for plasma sprayed coatings.

An improved bond coat, incorporating metallic or ceramic and cermets layers has been demonstrated to increase the thermal fatigue life of a plasma sprayed TBC by a factor of two or more. Utilizing this system, the second layer of the bond coat incorporates a fine dispersion of a particulate second phase in a MeCrAlY matrix. The second phase is required to have a coefficient of thermal expansion as low as possible or preferable lower than yttrium zirconium layer and it must be stable up to intended temperature, chemically inert with respect to the MeCrAlY matrix and must be chemically compatible with the thermal grown alumina scale.

INCAS has in progress evaluation experiments of the triplex layer type MeCrAlY/MeCrAlY 90% + Al2O3 10%/ZrO2. Y2O3 obtained by plasma spray technology. The achievement of some thin layers imposes the CVD, PVD, Sputtering, etc. technologies.

Within the consortium, in this direction, INCAS is able to participate especially in the achievement of some multifunctional layers, thermal shock stressed.

3.4.2.1. Development of fundamental knowledge

3.4.2.1.2 New generation of tools for advanced materials characterisation

Quick thermal shock test installation for multifunctional ceramic coatings

Protection layers and especial ceramics have main servitude lower resistance at thermal shock.

For aeronautical application, rockets, metallurgical, power industries, is important the behavior of this coatings in limited functional conditions - with additionally requests.

Thermal shock classical installation mentioned in literature has heating

cooling cycle with substantial low speed than extreme functional conditions. In the same

context are not testing methods in extreme condition, unanimous accepted.

The main characteristics of the proposed thermal shock installation:

  • testing sample dimensions-rectangle LxWxH {mm} - 25x25x2;or circular f 25x1÷2 mm
  • the test specimen materials: metals, alloys, composite materials, ceramic materials, coatings (enamel, multilayered, TBC, FGM, etc.)
  • maximum testing temperature: +1400 degrees Celsius
  • heating time from the environment temperature till the testing temperature:15÷150 sec
  • cooling time from the testing temperature till the environment temperature:15 ÷250 sec
  • temperature speed measurement : 150 ms
  • sample view during the test
  • temperatures measurement during all the time test
  • samples photo in the heating and cooling areas
  • samples lighting in the heating and cooling areas
  • manual cycle
  • automatic cycle
  • work parameters registration:
- environment temperature
- oven temperature
- sample temperature
- heating time
- cooling time
- cycle working time
- graphic and table display of samples temperatures against time and position during the test

This installation is absolutely necessary, in our opinion, for testing and selection of the ceramic layers in extreme functional condition, for industrial applications.

INCAS is able to conceive, design and achieve (in cooperation with European partners) quick thermal shock installation for ceramic layers by FGM type.

C-C nanocomposites

3.4.2.3. Engineering support for materials development

3.4.2.3.1. Materials by design: multifunctional organic materials

Nanocomposites epoxy-Montmorillonit

Nanocomposites are a new class of advanced, nanometer-scale multiphase polymer composites that often display many enhanced physical properties: strength, hardness, thermal and viscoelastic properties. Nanocomposites are synthesized by dispersing expholiated clays, nanometer particle and aggregates into a polymer matrix (epoxy) or by infiltrating epoxy into the interlayer structure of layered silicates.

INCAS in cooperation with ICECHIM Bucharest develop researches regarding nanocomposites epoxy- Montmorillonite (aluminum hydrate silicate), via second way. In the first stage some samples of epoxy resin as such and epoxy-10% Montmorillonite (weight) is performed.

The mechanical testing results up to date are synthesized in table 1.

 Epoxy resin characteristics with and without Montmorillonit Table no. 1

No.

Sample

Tensile Strength [MPa]

Young Module
E [MPa]

Hardness [shore]

1

Epoxy LY 554

110

28000

75

2

Epoxy LY 554+10% Montmorillonite

120-130

52000

83

It is to notice the significant effect of the Montmorillonit addition upon the elasticity modulus.

The researches will be continued with complementary studies regard nanocomposites-epoxy-glass fiber, nano epoxy-fibers composites and maybe nano epoxy-carbonnanotube, incorporated.

3.4.3.1. Development of new processes and flexible, intelligent manufacturing systems  

3.4.3.1.1. New production technologies for new micro-devices using ultra precision engineering techniques

Carbon – carbon composites nano-ceramic matrix

Carbon fiber and carbon-carbon was first developed for aerospace technology (component in missiles, reentry vehicles, in space shuttles as structural parts and as brake lining and brake disc material for civil and military aircraft). Materials and Tribology Department of INCAS realized performing carbon fiber (PAN precursor) and carbon-carbon composites, phenolic matrix.

Some characteristics of FC obtained are synthetised in table 2.

Characteristics of FC Table 2

Tensile strength [MPa]

E, Young Modulus [MPa]

Fibre diametre [milimicroni]

%C

Process out put

3.1x10 3

2.4x10 5

7

98.5

50%

In table 3 some characteristics of CF composites and C – composites are presented.

Mechanical and tribologies characteristics Table 3

No.

Material

Tensile stregnth [MPa]

Friction coefficient

1

CF – 2D tissue composite

750

0.13

2

CF – Uni directional composite

850

0.13

3

Chopped FC (3.5 mm) composites

300÷350

0.13

4

C-C composites 2D tissue

200÷250

0.13

For concordance in tribological and antioxidant properties of C-C composites distinct solutions was developed:

  • FC - fiber (unidirectional 2D tissue, chopped, felt preform) and phenolic matrix with 25% CSi (reported to fenolic resin)
  • Nanocomposites C-C ceramic matrix via so called LSI (Liquid Silicon Infiltration).

The sol gel SiO2 (50% weight reported to fenolic resine) infiltrated in a C-C by thermal treatment at 1600°C generates ceramic matrix (CSi). The results of tribological testing are presented in table no 4:

Friction coefficients for C-C composites Table 4

No.

Material

Friction coefficient

1

C-C composite

0.13÷0.14

2

C-C+25% C-Si composite

0.3÷0.35

3

C-C+50% SiO 2 colloidal composite

0.3÷0.35

In the future INCAS- Material and Tribology Laboratory aims to achieve carbon fiber composites ceramic matrix, via nanosilicium carbide-mesophase, or to use polymeric precursor (policarbosilane) for CSi matrix.