Manufacturing of Novel Nanostructured TiCrC Carbides Using Mechanical Alloying and Spark Plasma Sintering

Dense nanostructured carbides existing in ternary system Ti-Cr-C were elaborated thanks to a two-steps method. In the first step, nanostructured Ti0.9Cr0.1C carbides were prepared by high-energy planetary ball milling under various times (5, 10, and 20 h), starting from an elemental powder mixture of titanium, chromium, and graphite. In the second step, these nanostructured powders were used to produce densified carbides thanks to the spark plasma sintering (SPS) process under a pressure of 80 MPa. The temperature was fixed at 1800 & DEG;C and the holding time was fixed at 5 min. Microstructural characteristics of the samples were investigated using X-ray diffraction (XRD). Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) was used to investigate the morphology and elemental composition of the samples obtained using SPS. The novelty of this work is to understand the effect of SPS on the microstructural and electrochemical properties of the nanostructured Ti0.9Cr0.1C carbides. The XRD results showed that, during sintering process, the (Ti,Cr)C carbide was decomposed into TiC, Cr7C3, and Cr3C2 phases. An amount of iron was detected as contamination during milling, especially in the case of a sample obtained from 20 h milled carbide. The bulk obtained from the milled powders for 5 and 20 h present similar relative densities of 98.43 and 98.51%, respectively. However, the 5 h milled sample shows slightly higher hardness (93.3 HRA compared to 91.5 HRA) because of the more homogeneous distribution of the (Ti,Cr)C phases and the low iron amount. According to the 0.0011 mm/year corrosion rate and 371.68 k & omega;.cm(2) charge transfer resistance obtained from the potentiodynamic polarization and EIS tests, the 20 h carbide was the specimen with the highest corrosion resistance.