Rheological, porosimetric, and SEM studies of cements with additions of natural zeolites (chabazite, mordenite and clinoptilolite) were investigated. The addition of 5% zeolite to cement pastes had a plastifying effect. The increase in the rheological parameters of aqueous cement–zeolite suspensions began after additions of more than 10% zeolite. At a water/solid ratio (w/s) = 0.5 all compositions exhibited similar rheological behaviour for yield stress and maximum shear stress values. At lower w/s values the rheology depended on the zeolite used, decreasing in the order Sl (clinoptilolite, Nižny Hrabovec deposit, Slovakia), M (mordenite, Philipines), Bp (clinoptilolite, Beli Plast deposit, Bulgaria), NM (clinoptilolite, Saint Cloud deposit, New Mexico) and Ch (chabazite, Nasm Yan deposit, Korea).

After 28 days of hydration the mixtures containing 10% Bp clinoptilolite, mordenite, and Sl clinoptilolite (up to 30%) had unchanged specific pore volumes but additions of 10% and 30% of chabazite and NM clinoptilolite and of 30% mordenite and Bp clinoptilolite lead to increases in the total specific pore volume compared to the neat cement paste. Between the 28th and 180th days of hydration the specific volume of the pores in all the cement-zeolite pastes decreased due to the filling of the pores with products from the pozzolanic reaction between the zeolites and the hydration products of the cement.

The pozzolanic reaction between zeolite and the hydration products of cement is enhanced by the zeolite content in the samples and depends on the Si/Al ratio (clinoptilolite (Si/Al >4.5), mordenite (Si/Al >5), chabazite (Si/Al <2.5)) and the surface area (clinoptilolite from Slovakia has the smallest crystallites and, hence, the greatest reactive surface area).

In order to integrate porous dielectric materials into the next generation of Cu/low-k interconnect, the porous material has to be sealed against metal barrier precursor. We have reported pore sealants which forms ultra-thin (< 3 nm-thick) layer on top of the surface of porous low-k film while the pore sealant does not diffuse into pores. In this study, it was investigated how pore seal layer is formed on the surface of porous material and how pore mouths are sealed by pore seal layer. It was found that 1) thickness of the pore seal layer is well-controlled in the range < 5 nm, by varying spin rate and concentration of solid, 2) minimal thicknesses of the pore seal layer needed to achieve an efficient sealing for porous low-k films whose pore radius is 1.5 nm was 2.6 nm. 3) Larger pores, whose pore radius is 4.2 nm, were sealed completely with an expansion of our technology.

In the context of the preservation of the cultural heritage, it is important to understand the alteration mechanisms of the materials constituting historical monuments and architecture. Limestone especially is widely used in many French monuments exposed to an urban aggressive atmosphere affecting their durability. To better understand the alteration mechanisms, the first step is to characterize at different scales the stone material properties. In one hand, the pore network that drives the fluids transfer inside the materials was characterized. And on the other hand, the alteration layer formed on several decades aged materials was studied. Results on this fine-scale characterization are discussed.

Calcium sulfoaluminate (CSA) cements are being developed using a novel processing method having as its objective lowering specific CO2 emissions by ∼50% relative to a Portland cement benchmark. We need to be able to measure the properties of the products. Porosity and permeability measurements help define the engineering properties but their quantification is influenced by the choice of experimental protocols. In the present study we used ordinary Portland cement (PC) paste as a benchmark and hydrated ye’elimite, which is a main component of CSA cements, to understand its pore structure. We report on the use of synchrotron-sourced radiation for µCT (Computerized Tomography) and 3D image re-construction of the internal micro-pore structure of PC and ye’elimite-gypsum pastes. As a comparison, porosity and permeability measurements were traditionally obtained using Mercury Intrusion Porosimetry (MIP). The Mori-Tanaka method and the polynomial statistical model were used to analyze the effects of different 3-D micro-pore structures on mechanical properties. The results show that e micro-pore structures differ considerably between PC and ye’elimite pastes and their bulk modulus is significantly affected by the shapes of their micro-pore structures.

Pore sealing has become a critical issue for the implementation of porous low-k dielectrics and for realizing acceptable reliability performance of the interconnect. This study focuses on fabrication of ultra-thin, conformal and plasma resistant pore seal layer and on understanding parameters playing a role in sealing the surfaces of porous low-k films. It was found that 2.5 nm-thick pore seal layer shows a perfect toluene seal property for the porous low-k film whose pore radius is 1.48 nm. The pore seal layer still show a good toluene seal property after irradiation of He plasma at 250°C for 10 sec. The increments of dielectric constant by applying the pore seal layer and by the He plasma irradiation for 10 sec are 0.04 and 0.03, respectively. Interestingly, all of toluene seal property, refractive index of the bottom part of the film and dielectric constant started to deteriorate after irradiation of He plasma for 20 sec. It was suggested that when toluene seal property degrades, plasma would start diffusing into pores and both refractive index of the bottom part of the film and k value start to increase.

Positron annihilation lifetime measurements are performed for sol–gel-derived 70 mol% SiO2–30 mol% CaO bioactive glass. Strong positronium formation processes are shown to be an inherent feature for these kinds of materials. Observed orthopositronium (o-Ps) lifetimes show a three-modal distribution with lifetime values weighed at ∼2, ∼18, and ∼70 ns. The exposure of the investigated sol–gel-derived bioactive glasses to water vapor significantly modifies o-Ps lifetime distribution due to the penetration of water molecules into the nanopores, indicating high ratio of their interconnectivity. Classic Tao–Eldrup equation is used to relate the o-Ps lifetimes with the size of nanopores, whose distribution is verified by nitrogen adsorption porosimetry.

Important pore structure parameters related to mechanical properties and durability of cement-based materials can be determined by techniques such as scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and low temperature calorimetry (LTC). The methods provide information on porosity characteristics as pore volume, pore thresholds and/or pore size distribution in different size ranges and do therefore to a large extent supplement each other. Pastes of w/b=0.4 with 0%, 40% or 70% slag by volume were cured saturated at 20ºC for up to two years. The porosity was characterized by LTC, MIP, and SEM. Higher volume of pores was obtained by MIP compared to results obtained using LTC and SEM. Measured porosity was correlated with predicted porosity using information on the density and degree of hydration of the cement and slag. Porosity estimation showed best agreement with the porosity data measured by MIP. The use of slag showed the same trend for all tests: a higher total volume of pores, but a lower threshold pore size when compared with Portland cement paste. The findings illustrate the importance of measuring not only pore volume but also threshold pore sizes when characterizing porosity of cement-based materials with different binder compositions.

In this work a new generation of periodic mesoporous organosilica (PMO) low-k dielectrics with targeted k-values 2.0 and 1.8 is evaluated. In addition, impact of two different curing processes on properties of the mesoporous material is analyzed. It is shown that removal of templating organics with thermal annealing leads to formation of mechanically robust and chemically very stable material, while application of UV-assisted curing with broadband lamp (λ > 200 nm) causes pronounced decrease of film ability to sustain in diluted HF solution. The explanation of that phenomenon is given in terms of silica-ring structures formed within organosilica skeleton.

When clutch boards are fabricated as friction sheets in automatic transmission of motorcars, their useless fragments are disposed of. In this study, an effective reuse of their waste clutch boards will be proposed. Clutch boards are composed of diatomaceous earth, carbon powder/fiber and phenol resin. Excess carbon in carbonized clutch boards was reacted with SiO formed from Si and SiO2 at 1500 °C in Ar to produce porous SiC sheets (79% porosity). High temperature treatment at 1700-1900 °C in vacuum made it possible to control the pore size of SiC sheets, having a main pore diameter range of 10 to 20 μm.

SiC sheets with porosity (79% to <60%) were also fabricated by heating carbonized/impregnated sheets with phenol resin in SiO gas at 1500 °C. SiC sheets obtained by the repeated cycle of impregnation/decomposition of resin heating at 1700 °C gave a tensile strength of 19 MPa.

When Aluminum-tri-sec-butoxide (ASB) solution was impregnated into SiC sheets oxidized at 1000-1200 °C in air and heated at 1400-1500 °C in Ar, SiC-mullite composite sheets with porosity (77%) were produced.

Extended abstract to Symposium B

Thermoporometry was employed to monitor the mesopore evolution in wet, drying and heat-treatment stages of monolithic macro/mesoporous silica with SBA-15 like structure. Direct comparison of mesopores in wet state was only possible with the samples extracted with sulfuric acid. In good agreement with the preceding study, the sulfuric acid not only removed the surfactant but also modified the silica gel network into that with reduced amount of micropores and increased stability against the drying stress. Thermoporometry revealed that the structural evolution takes place completely in the wet condition, which accompanies a decrease in the thickness of non-freezable water.

Interaction of moisture with porous low-k films is evaluated by using in situ ellipsometry setup. The adsorbed water amount is calculated from change of refractive index measured during the adsorption. Pristine low-k films reversibly adsorb 2 - 5% of water that reflects presence of constitutive hydrophilic centrums. Plasma and thermal treatments increase the number of hydrophilic centrums. Once the amount of these centrums has reached a certain critical value sufficient to form a continuous water film, bulk water condensation is observed. Change of properties during the water adsorption in the damaged films is not fully reversible. Each additional adsorption cycle increases the dielectric function of the film because of decreasing porosity, increasing skeleton density and shrinkage. The pressure corresponding to the bulk condensation allows us to calculate internal contact angle (internal surface energy) of low-k materials. The water molecules adsorbed on separate OH groups play the role of a catalyst that hydrolyses the siloxane bridges initially present on hydrophobic surface.