• research of metal ageing processes and properties degradation under the impact of operational factors;

• assessment of reliability of power plant facilities and operating life-time extension;

• development of composites of multifunctional and structural properties from nanoscale materials;

• research of nanocomposite development in cement constructional materials;

• research of composition and properties of ceramics and ceramic coatings;

• testing of materials, assessment and analysis of their qualitative indicators.

 

 

In 2008 the Laboratory continued research on hydrogen and hydrides induced degradation of the mechanical and physical properties of zirconium-based alloys. The Laboratory participated in IAEA coordinated project Delayed Hydride Cracking of Zirconium Alloy Fuel Cladding. The objective of the project is to develop uniform experimental procedures, which will enable to assess velocity of delayed hydride cracking in zirconium-based alloy fuel cladding tubes and to determine the conditions inducing fuel cladding degradation. Obtained experimental data may be used in developing and validating predictive models of hydrogen induced cracking of fuel cell zirconium-based alloys, estimating hydrogen impact on physical and mechanical properties of alloys. These issues are important in dealing with problems of ensuring safe operation of nuclear power plants, they are also relevant in storage of spent nuclear fuel assemblies.

 

 

In 2008 several projects were carried out in investigating metal ageing processes, which take place in operating facilities of thermal power plants at high temperatures and under the impact of stresses. The problem of steel operation and its ageing at high temperature is relevant to many power enterprises. Results of these works and created methodology could be employed in Lithuanian power plant as well as in other power plants, in which constructional steels operate under high temperature and pressure conditions. Remaining lifetime assessment enables to optimize activities of renovation of power plant facilities. Implementing works in this research area a lot of attention is given to fundamental research of physical phenomena in steel structures.

 

 

Micro-structural changes of steel 12X1MФ, occurring while it is ageing. 1 – Non-operated steel, 2 – heated for 384 h at 700 ^oC, 3 – operated for 227000 h at 550 ^oC under 14 MPa

 

Together with the Laboratory of Nuclear Installation Safety, implementing project Justification of the Remaining Lifetime of Direct Steam Cut-off Valve with SC Lietuvos Elektrinė, state of metal of direct steam cut-off valve case has been investigated. Mechanical characteristics of steel were determined, x-ray investigations were carried out as well as optical, electronic and metallographic analysis, taking into account operational conditions.

 

Using contemporary finite element computation methodologies and considering changed properties of steel and occurred structural changes, resistance and remaining lifetime of valve case construction under given operational conditions was determined.

 

Project Justification of Service Time Extension of the Servodrives of Ignalina NPP Unit 1 Safety Protection System was carried out in the Laboratory of Materials Research and Testing. Specific complex experiments of fast acting protection system servo-drives, calculations and statistical reliability assessment were carried out to determine the real residual lifetime of servo-drives.

The COST Action 538: High Temperature Plant Lifetime Extension was carried out with the participation of 17 European countries. Main objective of the activity – development of advanced forecasting model of the remaining lifetime assessment of high temperature power plant equipment. Heat resistant steel 12X1MФ samples, aged under laboratory conditions and others operated in the power plant, were investigated using optical, scanning electron microscopy and X-ray diffraction. Variations of carbide content and phase composition were estimated qualitatively and quantitatively during the experiments. It was determined that X-ray diffraction analysis is a fast and informative estimation method of operational conditions of pearlite heat resistant steel.

 

It was suggested to employ steel ageing at high temperatures under laboratory to simulate processes, occurring while operating it under real conditions.

 

Due to alloyed element diffusion under ageing of heat resistant steel, phase composition of carbides changes. Changes of composition are determined using X-ray diffraction analysis. Ferrite and cementite (Fe3C), comprising the initial steel structure, gradually turn into thermodynamically more stable carbides (M23C6 and M7C3). In accordance with change of these carbides’ amount during steel ageing, its operational state is determined.

 

 

 

In 2008 researchers of the Laboratory joined activity COST MP0701 Composites with Novel Functional and Structural Properties by Nanoscale Materials, participating in the activity of the first working group WG1 Nanoparticles/Interfaces (selection of matrix and nanoparticles, production of nanoparticles, surface functionalisation/chemical treatments of nanoparticles). The objective of participating in the COST activity is to develop preparation methodology of polymer nanocomposite with epoxy matrix and nanosized filler, to investigate the impact of different factors (filler dispersion method, its chemical modification, selection of hardener and compatibility with filler) on intercalation/exfoliation of mineral filler in polymer matrix.

 

Participating in COST MP0701 activity Laboratory researchers cooperate with researchers from Kaunas University of Technology (Department of Chemical Technology).

 

 

In recent years, working together with the Laboratory of Plasma Processing, a lot of attention has been given to the application of nanotechnologies in cementious building materials. The project is carried out together with Vilnius Gediminas Technical University (Thermal Isolation Institute, Kaunas University of Technology, Physical Electronic Institute, JSC Betoneta and JSC Statizola. The objective of the project is development of novel cementious building materials, the properties of which are conditioned by nano-structures, developed in their structure.

 

 

 

 

Research is carried out analyzing principles of nano-structure formation of cementious composite materials with nanomodifiers and impact of these composites on product properties. Main work task of the year 2008 was extraction of nanomodifier “micro fiber” in plasmachemical reactor and investigation of fiber’s properties.

 

 

SEM pictures of the fiber

 

The micro fiber is produced from fluid catalytic cracking catalyst waste (ceolits), utilization of which is relevant from ecological and economical point of view. Research revealed that fiber may be used not only in compositions with portlandcement, but also in cementious compositions designed to be used at high temperatures. Fiber’s thermal endurance is higher than 1200 ^oC.

 

 

Together with the Laboratory of Plasma Processing COST action 533 activity Materials for Improved Wear Resistance of Total Artificial Joints is implemented. The main objective of the Action is to develop materials for improved wear resistance of artificial joints and enhance durability of artificial joints employing theoretical knowledge and practical experience of scientific participants of the action.

 

Participating in the activity of the 2nd working group Alternative Hard Bearing Couples for Artificial Hip Joints, which scientific programme is pointed on the alternative biomaterials, which exhibit better tribocorrosive properties, scientific research is focused on the investigation of the properties of bioinert ceramic coatings formed by plasma spray method on the titanium steel substrates for the development of artificial joints. Performed research revealed that plasma deposited ceramic coatings based on tetragonal zirconia and alumina exhibit good wear resistance and may be a good alternative material for artificial joints.

 

Researchers of the Laboratory perform activities providing accredited services, performing material testing and assessment of their quality (the laboratory is accredited for LST EN ISO/IEC 17025). The Laboratory successfully cooperates with industrial partners, performing research works and providing consultations in the field of product quality assurance.

 

In 2008 researchers of the Laboratory published 7 articles in science journals and 8 in reviewed conference materials, 4 science promotion articles in popular publications. Participated in 14 international and Lithuanian scientific conferences.