ABSTRACT In this study, it was studied that the abrasion resistance and characteristics of polymer composites with fly ash (FA). The epoxy based polymer composites are produced with resin and FA as mineral additive. Mixtures of different ratio by replacing the FA were added to the resin from 0 to 30% by weight. Polymeric samples were cured in air conditioning and they were taken from the molds after 24 hours. Polymeric samples gain ultimate strength after 7 days. Therefore, abrasion tests were performed on 7 aged specimens. Abrasion characteristics of polymer composites were defined by pin-on-disc test for 500 m under a dry friction condition and room temperature. Three types of loading conditions were carried out as 5, 10, 15 and 30 N. The hardness and wear resistance values increased with the increase in the content of fly ash. Showing the relationship between wear rate and hardness, an equation with parameters dependent on load was provided. There was an increase in the friction coefficient with an increase in the surface roughness values. In addition, dynamic friction was as a function of the wear rate. The wear surfaces of the polymer composites were analyzed using scanning electron microscopy. It was observed that the wear rate of the polymer composites and pure epoxy samples ranged from 17.82 to 172.96 mm3/Nm.

In the present study, the effects of the boriding process on adhesion and tribological properties of AISI 310 steel were investigated. Boriding was performed in a solid medium consisting of Ekabor-II powders at 1123 and 1323K for 2 and 6 h. The boride layer was characterized by optical microscopy, the X-ray diffraction technique and the micro-Vickers hardness tester. The X-ray diffraction analysis of the boride layers on the surface of the steels revealed the existence of FexBy, CrxBy and NixBy compounds. Depending on the chemical composition of substrates, the boride layer thickness on the surface of the AISI 310 steel was found to be 56.74 μm. The hardness of the boride compounds formed on the surface of the AISI 310 steel ranged from 1658 to 2284 HV0,1, whereas the Vickers hardness value of the untreated steel AISI 310 was 276 HV0,1. The wear tests were carried out in a ball-disc arrangement under a dry friction condition at room temperature with an applied load of 10N and with a sliding speed of 0.3 m/s, at a sliding distance of 1000m. The wear surfaces of the steel were analyzed using an SEM microscopy and X-ray energy dispersive spectroscopy EDS. It was observed that the wear rate of unborided and borided AISI 310 steel ranged from 4.57 to 71.42 mm3/Nm.

In this study, we studied the physical and mechanical properties of polymer composite with wastes that incorporating boron. The polymer composites were produced with epoxy based resin and wastes as mineral additive. The wastes were added to mixtures in different ratio by replacing the resin from 0 to 66% by weight. Slump-flow and viscosity tests are carried out on fresh samples after mixing. Composites were cured in air condition and they were de-molded after 24 hours. They gain ultimate strength after 7 days. Therefore, tests for characteristics were performed on 7 aged specimens. On the polymer composite samples, compressive strength, flexural strength, wear resistance, water absorption and density tests were performed. As a result, addition of the wastes that including boron increased the compressive strength of polymer composites; however, it made the composites more brittle material with low flexural strength.

<title>Abstract</title><p>Polymer surface coatings provide superior adhesion to substrates, some flexibility and corrosion resistance. On the other hand, 400,000 ton of boron wastes are generated each year. We have developed polymer composites based on epoxy resins containing up to 50 wt. % of boron wastes and determined their pin-on-disk dynamic friction, wear, Shore D hardness and surface roughness. The hardness and wear resistance increase with increasing boron waste concentration. An equation, with parameters dependent on the load, relating wear rate to hardness is provided. Dynamic friction increases with increasing surface roughness, as represented by the equation. Further, dynamic friction is an increasing function of the wear rate. Micrographs of pure epoxy without fillers shows traces after pin-on-disk testing, with tears, breaks and cracks. For the composites, we observe simpler and relatively homogeneous surfaces.</p>

In the present study, the corrosion behaviors of borides formed on cold work tool steel have been investigated in a 4% M HCl acid solution. Boriding was performed in a solid medium consisting of Ekabor-II powders at 850 and 950°C for 6 h. The boride layer was characterized by SEM, EDS, XRD and the hardness tester. XRD analysis of boride layers on the surface of the samples revealed the existence of FeB, Fe2B, CrB, Cr2B and MoB compounds. Depending on the chemical composition of substrates and boriding time, the boride layer thickness on the surface of the steel ranged from 13.14 μm and 120.82 μm. The hardness of the boride compounds formed on the surface of the samples ranged from 1806 to 2342 HV0,05, whereas Vickers hardness values of the untreated the samples was 428 HV0,05. The corrosion resistance of the borided steels was higher compared with that of the unborided steels. The borided steels increased the corrosion resistances of the steels 8-17- fold.

This study investigates the corrosion behaviors of plasma nitrided (PN) and borided AISI M2 steels. The PN process was carried out in a dc-plasma system at a temperature of 923K for 6 h in a gas mixture of 80%N2-20%H2 under a constant pressure of 5 mbar. The boriding process was carried out in Ekabor-II powder at a temperature of 1223K for 6 h. X-ray diffraction analysis on the surface of the PN and borided steels revealed the presence of FeB, Fe2B, CrB, MoB, WB, FeN, Fe2N, Fe3N and Fe4N compounds. Corrosion surfaces of the samples were analyzed using a SEM microscopy and X-ray energy dispersive spectroscopy EDS. The corrosion resistance of PN and borided AISI M2 steel is higher compared with that of untreated AISI M2 steel. Corrosion resistances of the PN and borided AISI M2 steel increased the 4-6- fold.