[ES] La tesis doctoral presenta y analiza la técnica de la cáscara cerámica, desde la creación del modelo en cera hasta la elaboración completa del molde de fundición específico de esta técnica. Se aportan referencias originales históricas y técnicas. Se realizan pruebas de porosidad y resistencia en función de los refractarios empleados y el número de capas, con conclusiones aclaratorias en cada capítulo. / [EN] This doctoral dissertation explains and analyzes the ceramic shell technique as a whole, starting from the creation of the wax model until the elaboration of the casting mold specific for this technique is finished. Original historical and technical references are provided. Different porosity and resistance tests are carried out depending on the refractory materials used and the number of layers. Clarifying conclusions are included in each chapter. / A Mr. David Reid, maestro de la técnica de la cáscara cerámica adaptada al taller de los escultores. Al Dr. Juan Carlos Albaladejo, director de la tesis doctoral, generoso maestro difusor de la técnica en las universidades españolas. Al Departamento de Ingeniería de los materiales (D. José Monzó y D. Pascual Hernández); al Dpto. de Pintura (Dr. Domingo Oliver y D. Manuel Guillén); al Institut de Ciències del Materials de la UV (Dra. Carmen Guillém); al IDM de la UPV (Dr. Ramón Martínez Mañez, Dr. Juan Soto y Dra. Mª Dolores Marcos); y al Departamento de Escultura (Paco P. Benavent y Dr. Pablo Sedeño) A Toni Tomás, Beatriz Piñero, Ángeles Afonso, Soledad del Pino, Mª Mar Caballero, familia Crespo Ricart y a Marian Alonso. / Marcos Martínez, MDC. (2001). Fundición a la cera perdida: Técnica de la Cascarilla Cerámica [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/157239

O processo de fundição por cera perdida representa, há muitos anos, o principal processo de produção gerador de peças de alta complexidade para atender os mais variados segmentos industriais tais como o automotivo, geração de energia, médico e bélico. A característica principal deste processo é a de obter cascas cerâmicas por meio de banhos de lama cerâmica ancorados por material refratário granulado aplicados sobre a superfície de modelos em cera com o formato da peça final. Estudou-se neste trabalho as propriedades do pó de telhas e também das cascas cerâmicas produzidas com lamas utilizando o próprio pó de telhas como material refratário tanto na lama primária quanto na lama secundária. O pó de telhas apresentou alta dispersão granulométrica #20-#325 mesh e em sua composição foram identificados compostos refratários importantes como a sílica e a alumina. Os ensaios realizados nas cascas cerâmicas confeccionadas com lamas de pó de telhas apresentaram resultados de módulo de ruptura à verde e calcinado (1000 °C) de respectivamente 1,02 MPa e 4,95 MPa e de permeabilidade a quente (1000 °C) 4,2 L/min. Os ensaios nas cascas cerâmicas utilizadas na indústria apresentaram resultados de módulo de ruptura a verde e calcinado respectivamente de 2,48 MPa e 5,7 MPa e permeabilidade de 3,8 L/min. As cascas cerâmicas confeccionadas com pó de telhas apresentaram módulo de ruptura inferior as cascas industriais, porém, com resultado de permeabilidade superior. As cascas cerâmicas com lamas de pó de telhas apresentaram bom comportamento durante o vazamento dos metais líquidos alumínio 356, bronze e ferro fundido cinzento, não foi observado quebras no molde e nem reação com o metal. As peças fundidas com as cascas cerâmicas produzidas com lamas de pó de telhas atenderam as tolerâncias dimensionais exigidas pela norma ABNT NBR 15990. / The lost wax process has for many years been the main production process generating parts of high complexity to meet the most varied industrial segments such as automotive, power generation, medical and military. The main feature of this process is to obtain ceramic shells by means of ceramic slurry baths anchored by granular refractory material applied to the surface of wax models in the shape of the final part. This work evaluated the properties of tile powder and also the ceramic shells produced with slurries using the tile powder itself as a refractory material in both primary and secondary slurries. The powder of tiles presented high particle size dispersion # 20 - # 325 mesh and in its composition important refractory compounds such as silica and alumina were identified. The tests carried out on the ceramic shells made with tile powder slurries showed green and calcined (1000 °C) modulus of 1.02 MPa and 4.95 MPa respectively and a heat permeability of (1000 °C) 4, 2 L / min. The tests in the ceramic shells used in the industry showed green and calcined rupture modulus results of 2.48 MPa and 5.7 MPa and permeability of 3.8 L/min respectively. The ceramic shells made with powder tiles had a lower rupture modulus than the industrial ceramic shell, but with a higher permeability result. The ceramic shells with tile slurries showed good performance during the casting of liquid aluminum 356, bronze and gray cast iron, no mold breaks and no reaction with the metal. The parts cast with the ceramic shells produced with tile powder slurries e met the dimensional tolerances required by ABNT NBR 15990.

Diploma thesis contains introduction into shell drying, its monitoring and influence on shell properties. The thesis works with the Cyclone machine described further. The shell drying process in the machine and experiments are carried out broadening understanding of functions and parameters of rapid drying process. Experiments comparing courses of drying under respective settings of Cyclone and under common drying in air-conditioned room are carried out. Also mechanical properties of commonly dried shells and shells made by the Cyclone machines are compared. The positive effect of the machine on the ultimate strenght of dried shells and positive effect on the drying speed has been confirmed.

This diploma thesis deals with the possibilities of optimization of ceramic shell molds in the method of investment casting. In the first part is mentioned a complete technological process of the method with focusing on production and quality control of the ceramic shell and components, from which it is produced. The experimental part is divided into two parts, in the first are results of laboratory tests, which were tested both the current ceramic shell and shells which have been considered as a possible replacement. In the second section were verified conclusions of the experimental findings and recommendations of the laboratory results in pilot plant conditions.

The purpose of this thesis is to assess the current state of production of ceramic shells in MESIT Foundry, a.s. and optimize it. The shells are evaluated in terms of their bending strength, gas permeability and microstructure. Subsequently, castings produced using the shells are evaluated with regard to number of non-conforming products and presence of defects. The final part seeks to compare different shells and outlines a possible new approach to the development of ceramic shells.

This diploma thesis deals with the choice of the most suitable composition of a ceramic shell mold for aluminum castings made by investment casting technology. The most suitable composition of the ceramic shells is chosen based on the results of the tests and from economic point of view. This thesis also deals with evaluation of the current conditions of the production of ceramic shells in Alucast, s.r.o and recommendations for stabilizing the process of manufacturing ceramic shell molds.

Diploma thesis is focused to the optimization of the ceramic shell for pouring thin walled aluminium castings by investment casting technology. The main objective is firstly to find the optimal binding system (ceramic slurry) and stucco materials for the shell and secondly its optimal structure and heat treatment (drying of each coat and final shell firing) before metal pouring.

The thesis continue thematically in the previous development of the wax mixtures for the company Fimes. The general description of the investment casting process from the production of the die to casting of the wax pattern is handled in the first part. It is followed by the summary of the previously carried out experiments on cracking the shells. The experimental part describes the individual operations from the production of tested wax patterns to casting in the Boilercláv. The newly developed wax mixture is compared to the wax mixture used by the company Fimes. The experiments focus on the possibility of cracking the shells during the casting process and the dimensional stability of wax mixtures.