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The AISI 52100 is a tool steel used in industry to produce bearings. After the end of its life cycle, it is remelted or discarded in deposits. The powder metallurgy rises as an alternative to recycle this material without any waste. The steps used to produce the AISI 52100 steel by powder metallurgy included: Machining with speed of 45 rpm, high energy ball milling of the scraps during 30 hours with mass/sphere relation of 1:15 and speed of 400 rpm, uniaxial pressing using 175 MPa and sintering through 30 minutes at 1200ºC. Also, were incorporated 1%, 3% and 5% of alumina particles in the milling process to increase the milling efficiency and mechanical strength after sintering. The results of microstructural and mechanical analysis indicated that the alumina addition during the milling process increased the AISI 52100 steel properties, being 3% the percentage proved as the most efficient among all additions.

The AISI 52100 is a tool-type steel and is more often used in industry for the production of bearings. After the end of its life cycle, it is discarded or remelted, but both processes are considered expensive. Thus, the possibility of reusing this material through the powder metallurgy (PM) route is considered advantageous, since it transforms a waste into another product. To obtain the starting powders, the AISI 52100 steel scrap was submitted to a process of high energy ball milling, which was milled pure and with 1 and 3 % of niobium carbide (NbC) additions. Those additions were performed with the intention of increasing the milling efficiency of the steel, through formation of a metal-ceramic composite with a ductile-fragile behaviour. To determine the morphology and particle size, scanning electron microscopy (SEM) and particle size distribution tests were used. The results indicated that with the carbide addition, a significant increase in the milling efficiency was achieved, being possible to obtain nanoparticles after 20 hours of milling time.

Metallic biomaterials are widely used for implants and dental and orthopedic applications due to their good mechanical properties. Among all these materials, 316L stainless steel has gained special attention, because of its good characteristics as an implantable biomaterial. However, the Young’s modulus of this metal is much higher than that of human bone (~193 GPa compared to 5–30 GPa). Thus, a stress shielding effect can occur, leading the implant to fail. In addition, due to this difference, the bond between implant and surrounding tissue is weak. Already, calcium phosphate ceramics, such as beta-tricalcium phosphate, have shown excellent osteoconductive and osteoinductive properties. However, they present low mechanical strength. For this reason, this study aimed to combine 316L stainless steel with the beta-tricalcium phosphate ceramic (β-TCP), with the objective of improving the steel’s biological performance and the ceramic’s mechanical strength. The 316L stainless steel/β-TCP biocomposites were produced using powder metallurgy and functionally graded materials (FGMs) techniques. Initially, β-TCP was obtained by solid-state reaction using powders of calcium carbonate and calcium phosphate. The forerunner materials were analyzed microstructurally. Pure 316L stainless steel and β-TCP were individually submitted to temperature tests (1000 and 1100 °C) to determine the best condition. Blended compositions used to obtain the FGMs were defined as 20% to 20%. They were homogenized in a high-energy ball mill, uniaxially pressed, sintered and analyzed microstructurally and mechanically. The results indicated that 1100 °C/2 h was the best sintering condition, for both 316L stainless steel and β-TCP. For all individual compositions and the FGM composite, the parameters used for pressing and sintering were appropriate to produce samples with good microstructural and mechanical properties. Wettability and hemocompatibility were also achieved efficiently, with no presence of contaminants. All results indicated that the production of 316L stainless steel/β-TCP FGMs through PM is viable for dental and orthopedic purposes.

The Vanadis ® 8 is a tool steel used in the manufacture of dies, punches and tools. It has a high carbon content combined with chromium, molybdenum and vanadium, and presents good performance in its mechanical properties. Usually, its chips obtained by machining are sold to companies that use remelting. However, this technique is considered expensive and harmful to the environment. Therefore, this work aimed to analyze the efficiency of the addition of vanadium carbide (VC) and molybdenum carbide (Mo 2 C) in the high energy ball milling of the Vanadis ® 8 steel. Microstructural analysis were performed in the pure steel and with 3% of VC and Mo 2 C additions. The milling parameters used were: speed of 350 rpm, ball-to-powder weight ratio of 15:1 and times of 4, 8 and 12 hours. The results indicated that the Vanadis ® 8 steel milled with VC presented the best microstructural results in all of the conducted tests.

The 316L stainless steel (316L SS) is one of the most used metallic materials for implants, due to its high mechanical properties and low cost. However, it is bioinert. One possibility to improve its biocompatibility is the production of a composite with β-tricalcium phosphate (β-TCP) addition. This study investigated the mechanical behavior of 316L SS/β-TCP composites through powder metallurgy. For this, used were 3 compositions, with 0 %, 5 % and 20 % of β-TCP. The compositions with 5% and 20% were milled during 10 hours with a mass/sphere ratio of 1:10 and 350 rpm. All compositions were uniaxially pressed with 619 MPa and sintered during 1 hour at 1100°C. The microstructural and mechanical evaluations were performed through scanning electron microscopy, density and compressive strength. The results indicated that, by increasing the percentage of β-TCP in the compositions, the mechanical resistance decreases, as a consequence of its low load support.

There are a class of material widely used in bone tissue repair. This material is calcium phosphate ceramics (CPCs)that can be used on two phases: α and β. However, β-TCP is more used in bone regeneration than α–TCP due to the biocompatible and bioactive properties.In the present work evaluate the influence of these two distinct processes to deagglomeration and the consequence in the particle size of the β-TCP obtained through solid-state reaction. Among all of the routes used in research and industry to reduce the particles size of different materials, the high energy ball milling is one of the most effective, due to the high rotation speed that this process achieves. The deagglomeration through agate mortar is considered a cheaper process when compared with the high energy ball milling. The characterization of both powders, deagglomerated in high energy ball milling and agate mortar, was realized through scanning electron microscopy, to analyze the powder morphology, and laser granulometry, to determine the size of the particles. Also, the forerunner powder was previously submitted to x-ray diffraction to confirm the formation of the β-TCP phase. The analysis through x-ray diffraction confirmed that the phase formed during the calcination process corresponded to the β-TCP. The results obtained after the deagglomeration processes indicated that the morphology was predominantly irregular for both powders. In relation to the granulometry, the deagglomeration performed through agate mortar showed to produce particles with smaller size (11,4µm e 0,9µm) and heterogeneous distribution, while the high energy ball milling process produced particles with larger size (11,4µm a 1,8µm) and higher homogeneity.