The production process of prosthetic restorations runs in two stages. In the first stage, the prosthetic foundation is produced of metal
alloys. In the second stage, a facing material is applied on the produced element. In both stages, the wettability is significantly important,
as well as the free surface energy relating to it. The quality of the obtained cast depends on the surface phenomena occurring between the
metal alloy and the material of which the casting mould is made. The performed examinations also point to a relation between the ceramics
joint and the base, depending on the wetting angle.
The aim of the presented paper was to examine influence of the composition of a Ti(C,N)-type coating on bases made of the Ni-Cr
prosthetic alloy on the wettability and the surface free energy.
The test material were disks made of the Ni-Cr alloy with the diameter of 8 mm. The disks were divided into five groups, which were
covered with Ti(C,N) coatings, with different amounts of C and N in the layer. In order to determine the surface free energy (����), the
wetting angle was measured. Two measure liquids were applied: distilled water and diiodomethane.
The obtained results of the measurements of the water-wetting angles suggest that together with the increase of the ratio of nitrogen to
carbon in the Ti(C,N) coating, the surface hydrophobicity increases as well. In all the samples, one can see a large difference between the
energy values of the polar and the apolar components. The high values of the polar components and the low values of the apolar ones make
it possible to conclude that these surfaces exhibit a greater affinity to the polar groups than to the apolar ones.
On the basis of the analysis of the surface free energy, one can state that covering the alloy with Ti(C,N)-type coatings should not decrease
the adhesion of the ceramics to the alloy, whereas TiC coatings should lead to the latter’s improvement. Due to their hydrophilicity, TiC
coatings should decrease the adhesion of bacteria to the surface and hinder the formation of a bacterial biofilm.
Air abrasion process is used for cleaning casting surface of prosthetic components, and to prepare the surface of these elements for the
application of veneering items. Its side effect, however, is that abrasive particles are embedded in the treated surface, which can be up to
30% of the surface and it constitutes the side effect of this procedure. Such a significant participation of foreign material can not be
indifferent to the properties of the surface. Embedded particles can be the place of stress concentration causing cracking of ceramics, and
may deteriorate corrosion resistance by forming corrosive microlinks. In the latter cases, it would be advisable to remove elements
embedded into the surface. The simplest method is chemical etching or electrochemical one. Nevertheless, these procedures should not
significantly change the parameters of the surface. Among many possible reagents only a few fulfills all the above conditions. In addition,
processing should not impair corrosion resistance of titanium, which is one of the most important factors determining its use as a prosthetic
restoration in the mouth. The study presented results of corrosion resistance of titanium used to make prosthetic components by means of
casting method, which were subjected to chemical processing designed to remove the embedded abrasive particles. The aim of the study
was to investigate whether etching with selected reagents affects the corrosion resistance of titanium castings. For etching the following
reagents were used: 30% HNO3 + 3% HF + H2O, HNO3+ HF+ glycerol (1:2:3), 4% HF in H2O2, 4% HF in H2O, with a control
sandblasted sample, not subjected to etching. Tests demonstrated that the etching affected corrosion properties of test samples, in each case
the reduction of the corrosion potential occurred - possibly due to the removal of particles of Al2O3 from the surface and activation of the
surface. None of the samples underwent pitting corrosion as a result of polarization to 9 V. Values of the polarization resistance, and
potentiodynamic characteristics indicated that the best corrosion resistance exhibited the samples after etching in a mixture of 4% solution
of HF in H2O2. They showed very good passivation of the surface.
The paper presents the microstructure and selected properties of ausferritic nodular cast iron annealed at the temperature 520 and 550°C.
This choice was dictated by the temperatures used in the practice of nitriding. Nodular graphite in cast iron was obtained with use of
Inmold process. Cast iron containing molybdenum and copper ensuring obtaining an ausferrite in the cast iron matrix without the use of
heat treatment of castings was tested. The effect of annealing temperature on the microstructure and the kind of fracture of the ausferritic
nodular cast iron was presented. The effect of an annealing temperature on hardness, impact strength and the microhardness of ausferritic
nodular cast iron matrix was shown too. The lamellar structure of phases in the cast iron matrix after annealing has been ascertained. There
has been an increase in hardness of an annealed cast iron and microhardness of its matrix. The reduction in the impact strength of the cast
iron annealed at 520 and 550°C was approximately 10-30%. Both an increase in the hardness of cast iron as well as an decrease in its
impact strength is probably due to the separation of secondary carbides during the heat treatment.
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