A new concept for the eco-friendly structural colorization of anodic titania: Photonic crystal structure

Structural colorization with photonic crystal structures draws high attention with fadeless bright color, combined with low toxic and eco-friendly features. It has been suggested for the first that the Titanium (Ti) surface coloration, which was not explained properly until now, is due to the photonic crystal structure. A dyeing process to be applied on the Ti/TiO2 will dampen their photocatalytic properties. However, the thin film grown on the Ti surface by the suggested anodizing process allows the formation of harmless structural colors and keeps photocatalytic performance. Ti substrates were anodized in HF and H3PO4 based solutions at voltage values between 10 V and 80 V. Structural, morphological, optical, and photocatalytic properties of the TiO2 thin films were characterized in order to determine anodization solution type and voltage. Similar to some butterfly wings, it is mentioned that the repeated lamellar and porous structures observed on the surfaces cause photonic crystal interactions with dielectric variations. It can be said that the anodization voltage value but not the anodization solution type can control the obtained structural violet, blue, yellow, orange, and red colors. Samples anodized at lower voltages exhibited better photocatalytic performance due to higher photon harvesting. Thus, we have proved in our study that both the photocatalytic property is not extinguished and that structural colors can be obtained

Nanoindentation and Corrosion Behavior of Additively Manufactured Ti-6Al-4V Alloy for Biomaterial Applications

In this study, the effect of different laser beam power on the nanoindentation and corrosion properties of Ti-6Al-4V alloys fabricated direct metal laser sintering (DMLS) method was investigated. Ti-6Al-4V samples were fabricated by DMLS method with three 34.72 J/mm3, 64.81 J/mm3 and 83.33 J/mm3 energy densities named as sample 1, sample 2 and sample 3, respectively. The microstructure and crystalline phase of Ti-6Al-4V samples were analyzed by optical microscope, SEM and XRD devices. Microstructural examinations showed that microstructure of Ti-6Al-4V samples consisted of the prior columnar β grains and α/α´ phases. The β phase proportion soared with rising laser beam power. Nanoindentation results illustrated that the order of reduced elastic modulus (Er) values was sample 1 > sample 2 > sample 3. The order of hardness (H) values followed sample 1 > sample 2 > sample 3. The H/ Er ratios were found to be 0.0338, 0.0333, and 0.032 for samples 1, 2, and 3, respectively. The H3/Er2 ratios were estimated to be 0.00734 GPa, 0.00633 GPa, and 0.00513 GPa for samples 1, 2, and 3, respectively. The presence of high values means better anti-wear capacity and good resistance to deformation for samples based on nanoindentaion findings. Moreover, electrochemical measurements depicted that the value of corrosion current density (icor) of the samples ordered as sample 3 > sample 2 > sample 1. The sample 1 exhibited better corrosion resistance than other samples. The findings showed that as the laser power is low, DMLS Ti-6Al-4V samples potentially have better mechanical and corrosion performance due to low β content and high α´ phases in the microstructure

INVESTIGATION OF GRAPHITE NANO PARTICLE ADDITION ON THE PHYSICAL AND MECHANICAL PROPERTIES OF ZA27 COMPOSITES

The physical and mechanical properties of composites consisting of ZA27 alloy reinforced with nano-sized graphite particles were investigated with the main objective of understanding the effect of the nano particulate reinforcement. These properties were determined by measuring the density, hardness and tensile strength values. The microstructure of the ZA27-Graphite (Gr) nanocomposites was investigated using a scanning electron microscope (SEM). The results indicated that density values of nano graphite added nanocomposites (GANs) decrease with increasing graphite rate while porosity ratio increases. Also the UTS and Brinell hardness values decreased with increasing graphite content

Effect of Nano-sized B4C Addition on the Mechanical Properties of ZA27 Composites

In order to understand the influence of nano-sized B4C additive on ZA27 alloy, mechanical and physical properties of ZA27-B4C nanocomposites were investigated in terms of B4C content. While physical properties were determined in terms of microstructural studies, density and porosity tests, mechanical properties were determined in terms of ultimate tensile strength (UTS) and hardness experiments. Morphological and microstructural studies were carried out with scanning electron microscopy (SEM). The experimental results indicate that nano-sized B4C can be used to enhance the mechanical properties of ZA27 alloy effectively. The highest mechanical performance can be obtained at ZA27-0.5% B4C (in weight) nanocomposite with values of tensile strength (247 MPa) and hardness (141,18 BH) and low partial porosity (0.5%). After a pick point, increasing B4C ratio may cause the formation of agglomeration in grain boundaries, that's why density, tensile strength, and hardness values are declined

Novel ZA27/B4C/Graphite Hybrid Nanocomposite-Bearing Materials with Enhanced Wear and Corrosion Resistance

In this study, nanosized B4C and graphite-reinforced ZA27 matrix hybrid nanocomposites were produced with mechanical milling followed by hot pressing. The friction coefficient values of nanocomposite samples remarkably decreased from 0.5036 (+/- 0.085) to 0.2575 (+/- 0.021) with the increase of milling time to 24 hours for nanocomposite powders. That was almost two times lower than those of unmilled nanocomposites. It was determined that the good distribution of reinforcement particles in the microstructure and low grain size allowed the formation of a protective oxide layer against corrosion. The corrosion resistance of the nanocomposite materials obtained from nanocomposite powders milled for 24 hours was quite superior to the others. The results revealed that the corrosion rate values were 29.068 and 4.033 mpy for hybrid nanocomposite samples produced from unmilled and milled powders for 24 hours, respectively