Tribological performance of TiN and TiCN coatings on a working tool steel

M. T. Hernández-Sierra,L. D. Aguilera-Camacho,Arturo Ponce,J. S. García-Miranda,K. J. Moreno 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.8

Although the applications of TiN and TiCN coatings are extensive, their mechanical and tribological properties are influenced by the substrates in which they are deposited. The present work is focused on the tribological performance of TiN and TiCN coatings on a working tool steel. Besides, adhesion and microhardness tests were carried out. The adhesion performance of both coatings resulted in class 1, according to CEN/TS 1071-8 standard, which allows observing the quality of adhesion. The composite microhardness was investigated by the analysis of relative indentation (β). Pin-on-disk tests were performed in dry and lubricated condition at 100 °C against tungsten carbide (WC). Low friction coefficients of µ k = 0.08 for TiN and µ k = 0.03 for TiCN were obtained in lubricated conditions. Wear mechanisms were analyzed by scanning electron microscopy (SEM). Abrasive wear was observed as the principal wear mechanism in dry condition, while in lubricated conditions wear signals seem to be scarcely noticeable.

Embedded Haptic Device Implementation for Soft Tissue Rendering

Humiko Yahaira Hernández Acosta,Alejandro Miranda Cid,Alejandro Tonatiu Velázquez Sánchez,Mario Ramírez-Neria,Guillermo Manuel Urriolagoitia Calderón 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.10

In this work, a haptic robotic device and its real-time virtual reality interface, deployed in an embedded computational platform is developed, in order to simulate soft tissue rendering contact forces and effects. A control scheme based on a bilateral tele-operation system is proposed recreating a multimodal interaction between the surgical trainer (operator) and the virtual robot (slave) in force-visual feedback environment. The virtual interaction object was modeled as a restriction in the haptic engine, it was implemented with an orthogonal decomposition of contact forces algorithm, generating two independent dynamics and recreated exponential deformation forces, like ones present during the manipulation of real organic tissue. The proposed model contains the biomechanical properties of a soft tissue (pork liver), characterized in an experimental compression test with an indenter.

Production of Al2O3/Ti/TiN functional materials by means of nitriding in ammonia salts of Al2O3/Ti composites

Elizabeth Refugio-García,José G. Miranda-Hernández,José A. Rodríguez-García,Enrique Rocha-Rangel 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.3

The production of Al2O3/Ti/TiN functional materials through the nitriding in ammonia salts of previously Al2O3/Ti fabricated composites was achieved. The matrix for the preparation of the functional materials is to create an Al2O3-based composite that presents a fine and homogeneous dispersions of very fine metallic particles of Ti. After the nitriding, microstructural observations were carried out on the transverse zone of the materials’ surface showing the presence of a very thin film of about 20 μm of a constituent that was identified with the help of EDS as TiN. In addition, measurements of micro-hardness on the surface and in the core of the functional material were realized in order to determine the effect of nitride formation on the hardness.

Production and characterization of Al2O3-Cu composite materials

Enrique Rocha-Rangel,José G. Miranda-Hernández,Socorro Moreno-Guerrero,Ana B. Soto-Guzmán 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

Using an intense powder mixture of Al2O3 with different copper contents (1, 5, 10, 20 or 30 mass %) several Al2O3-Cu composite materials were fabricated. The microstructure of the composites was observed by optical and scanning electron microscopy. The observations show a microstructure formed by an Al2O3 ceramic matrix with fine Cu metallic networks. Due to the liquid sintering mechanism, the relative density reached by the samples was higher than 95%, this together with the fine and homogeneous microstructure present in the samples let us obtain composite materials with good values of toughness, hardness, elastic modulus and electrical properties. The incorporation of a ductile metal inside a hard ceramic matrix increments its toughness. The probable toughening mechanism is crack bridging due to the presence of a homogeneous ductile metal networks in the material’s microstructure. The values of density, hardness, elastic modulus and electrical resistance of the composites are directly dependent on the copper content in the matrix, because with an increase in copper content the density of the composites is larger, whereas, the hardness, elastic modulus and electrical resistance are reduced. Using an intense powder mixture of Al2O3 with different copper contents (1, 5, 10, 20 or 30 mass %) several Al2O3-Cu composite materials were fabricated. The microstructure of the composites was observed by optical and scanning electron microscopy. The observations show a microstructure formed by an Al2O3 ceramic matrix with fine Cu metallic networks. Due to the liquid sintering mechanism, the relative density reached by the samples was higher than 95%, this together with the fine and homogeneous microstructure present in the samples let us obtain composite materials with good values of toughness, hardness, elastic modulus and electrical properties. The incorporation of a ductile metal inside a hard ceramic matrix increments its toughness. The probable toughening mechanism is crack bridging due to the presence of a homogeneous ductile metal networks in the material’s microstructure. The values of density, hardness, elastic modulus and electrical resistance of the composites are directly dependent on the copper content in the matrix, because with an increase in copper content the density of the composites is larger, whereas, the hardness, elastic modulus and electrical resistance are reduced.

A New Mixture Criterion for the Improvement of the Compressive Strength of Adobe Using Zeolite as Stabilizer

Rosa Angélica Lara-Ojeda,Juana María Miranda-Vidales,Lilia Narváez-Hernández,Juan Manuel Lozano de Poo 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.8

The use of zeolite as a stabilizer for adobe has proven to have the ability to improve its physical and chemical properties. This is shown in the positive results in terms of strength gain and water absorption resistance in adobe blocks. In this work, an investigation was carried out to evaluate the use of zeolite as adobe stabilizer. The adobes were made with two different types of soil with different content of zeolite (5, 10, 15, 20% by weight) maintaining the zeolite-lime ratio 1:1. The samples were tested on compressive strength and water absorption. The deterioration of the adobes was analyzed under conditions of extreme humidity. The results of this study revealed that adobe behavior is influenced by the synergistic relationship between soil, zeolite and lime, showing significant changes in compressive strength even under extreme humidity conditions. It was also observed that the chemical composition of the soil influenced the development of the pozzolanic reaction. The stabilization of adobes with 15% of zeolite showed the best mechanical behavior, before and after deterioration assay. Hence, zeolite promises to be a good alternative as a stabilizer in adobe construction systems.

Strength and Corrosion Studies of Mortars Added with Pozzolan in Sulphate Ions Environment

Roxana I. Martínez-Rosales,Juana María Miranda-Vidales,Lilia Narváez-Hernández,Juan Manuel Lozano de Poo 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.12

The pozzolanic materials have the capacity to modify the performance of Portland cement (PC) mortars. When they are used as supplementary materials, the physical-chemical properties such as compressive-strength and resistance to aggressive environments (chloride, sulphate, acids) are improved. In this article, a study was carried out to evaluate the effects of the addition of two natural pozzolans: volcanic pumice and zeolite. Both used as substitutes for PC in mortars based on cement, considering mechanical strength and the aggressive effect of sulphate ions. Furthermore, the electrochemical behavior of the steel rebar embedded in these mortars was studied during 730 days of exposition to aggressive conditions. The results revealed that the development of the compressive strength of mortars with pozzolans added reached similar values to the reference mortar. It was possible to observe that the addition of the pozzolan suppresses the ettringite formation proportionally to the pozzolan content. The corrosion resistance of the steel improves with the addition of pozzolans after 730 days of exposition at sulphate environment. The results of this study revealed the feasibility to use natural pozzolan as an additive during the preparation of cement up to 25% without significant changes of the physical-chemical properties of the mortars.

Fracture toughness enhancement for metal-reinforced alumina

Enrique Rocha-Rangel,Elizabeth Refugio-García,José G. Miranda-Hernández,Eduardo Terrés-Rojas 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6

With the idea to determine ways of tailoring alumina (Al2O3) in order that one or more toughening mechanisms are activated in service, investigations about the production of Al2O3-based composites with different reinforcement metals and intermetallics have been carried out. The synthesis of composites materials has been made by means of both; liquid and solid pressureless sintering of an intensive mechanical mixture of powders. With the use of some metals in the chemical formulations, significant improvements in ceramic toughness have been reported. From the fracture toughness measurements and microstructural observations, it can be concluded that the toughening mechanism in Al2O3/metal reinforced composites is due to crack bridging and crack deflection. With the idea to determine ways of tailoring alumina (Al2O3) in order that one or more toughening mechanisms are activated in service, investigations about the production of Al2O3-based composites with different reinforcement metals and intermetallics have been carried out. The synthesis of composites materials has been made by means of both; liquid and solid pressureless sintering of an intensive mechanical mixture of powders. With the use of some metals in the chemical formulations, significant improvements in ceramic toughness have been reported. From the fracture toughness measurements and microstructural observations, it can be concluded that the toughening mechanism in Al2O3/metal reinforced composites is due to crack bridging and crack deflection.