A Techno-Economic Assessment Methodology for Advanced Additive and Joining Processes

Integrated manufacturing systems, a combination of subtractive, additive, and joining processes, provide a competitive advantage for manufacturing organizations. As product designs become more complex and capital more scarce, an ideal combination of advanced manufacturing technologies (e.g., powder bed fusion or friction welding), in tandem with traditional subtractive manufacturing systems, can optimize the production of high-value products. However, adoption of advanced additive and joining processes (AAJPs) on a large-scale has been obstructed by technical and economic barriers. Techno-economic analysis is a tool that can help justify the large-scale implementation of integrated manufacturing systems, and realization of potential cost and performance efficiencies. Consequently, a methodology has been developed to understand the impacts of competing manufacturing decisions for AAJPs. The approach has been further developed and applied to a case study for aerospace applications. Major contributions include development of integrated process selection algorithms and cost analysis models. Results demonstrate the feasibility of this strategy to evaluate competing advanced manufacturing technologies

Polishing of CVD-Diamond Substrates Using Reactive Ion Etching

Multichip modules (MCM)have proved to be a viable packaging technology for achieving small size and high performance. By their nature, MCMs typically integrate multiple bare die into a module that can be the plastic or ceramic package. As a result, the MCMrequires an efficient mechanism for removing excess heat. Diamond with its excellent thermal conductivity, is the ideal choice as a substrate material for these applications. Chemical vapor deposited (CVD) diamond substrates makes possible the practical realization of a novel diamond based 3-D MCM. However, the diamond films grown by CVD technique are polycrystalline and have non-uniform filmroughness and randomly faceted crystals. These non-planar surfaces reduce the diamond\u27s thermal management efficiency. Therefore, itbecomes imperative that the asdeposited diamond films be polished for use inMCMs. Chemical assisted mechanical polishing (CAMP) technique has been developed at HiDEC,University of Arkansas. In this technique diamond is lapped against an alumina plate under a load in the presence of certain chemicals. Although CAMP technique reduces the lapping time considerably, stillnewer techniques must be developed to reduce polishing cost further. We are currently using reactive ion etching (RIE) to substantially reduce the polishing time. Preliminary studies using reactive ion etching showed etch rates of 500 - lOOOA/min at low pressures. These etched films showed a considerably higher polishing rate (using CAMP technique) than the nonetched films. Changes in the morphology and structure of the diamond films due to etching and polishing were characterized by scanning electron microscopy (SEM), Dektak profilometer and Raman spectroscopy. This paper presents a systematic study ofRIEand CAMP of CVD-diamond substrates

A comparative study of the dry and wet nano-scale electro-machining

In recent years, a nano-electromachining (nano-EM) process based on a scanning tunneling microscope (STM) platform has been demonstrated. Nano-EM is capable of machining nano-features, under both, liquid dielectric (wet nano-EM) and air dielectric (dry nano-EM) media. The objective of this paper is to present a comparative study between the wet and dry nano-EM processes based on process mechanism, machining performance, consistency and dimensional repeatability of these two processes. The comparison of the two processes has been conducted at near field nano-EM, where the gap between the tool electrode and workpiece is 2 nm and the machining is performed at room temperature and pressure (macroscopically). The major differences in the process mechanism are due to the media at dielectric interface, the breakdown field strength and breakdown characteristics of two dielectrics and therefore, the material removal mechanism. It is reported that the material removal mechanism of wet nano-EM is associated with field emission-assisted avalanche in nano-confined liquid dielectric, whereas, the material removal mechanism in dry nano-EM is associated with field-induced evaporation of material. The differences have also been observed in the machining performance, dimensions of the machined features and repeatability of the nanoscale machined features. The self-tip-sharpening process with the continuation of machining has added several advantages to dry nano-EM over wet nano-EM in terms of dimensions of the nanoscale features, repeatability and machining performance

Method of planarizing polycrystalline diamonds, planarized polycrystalline diamonds and products made therefrom

A method of planarizing a diamond film which generally includes orifices in the surface is described. The method includes first polishing the diamond film surface to reduce the surface roughness. A filler material is applied to the surface of the film to fill the orifices in the film. The film is polished to remove excess filler material and expose the diamond film surface. Also disclosed are planarized diamond films diamond substrate having a polished surface of both diamond and filler material and a variation in thickness of less than 8 percent

Method of electroplating a substrate, and products made thereby

Disclosed is an electroplating method and products made therefrom, which in one embodiment includes using a current density to form a conductive metal layer having a surface roughness no greater than the surface roughness of the underlying member. In another embodiment of electroplating a substrate surface having peaks and valleys, the method includes electroplating a conductive metal onto the peaks to cover the peaks with the conductive metal, and into the valleys to substantially fill the valleys with the conductive metal

Passivation of material using ultra-fast pulsed laser

The surface of a semiconductor material, e.g., gallium arsenide, is passivated by irradiating the surface with ultra-short laser pulses, until a stable passive surface is achieved. The passive surface so prepared is devoid of a superficial oxide layer

Apparatus for and method of polishing and planarizing polycrystalline diamonds, and polished and planarized polycrystalline diamonds and products made therefrom

Disclosed are polished and planarized diamond films and a method and apparatus for polishing and planarizing diamond films. The method generally includes mechanical polishing of the diamond film against a ceramic surface in the presence of a treating agent of potassium nitrate and a polishing agent of potassium hydroxide. The produced films have an average surface roughness on the order of 0.05 microns, a planarization uniformity within eight percent, and are relatively free of process-induced contaminants

(Re)pensando a perturbação de hiperatividade com défice de atenção: contributos de um estudo de caso

A Perturbação de Hiperatividade e Deficit de Atenção (PHDA) constitui uma temática atual no âmbito das problemáticas do desenvolvimento da infância e adolescência, não só pelo número crescente de casos, mas também pelo facto de a etiologia ainda ser desconhecida. A família constitui o núcleo educativo fundamental que acompanha o desenvolvimento da criança. Neste contexto, destacamos as práticas parentais, as interações e os vínculos afetivos, fatores relevantes no quadro do funcionamento familiar e parental. Apresentamos ao longo deste trabalho diversas questões relativas à PHDA, repensando a sua conceptualização, a análise diferencial e a influência que este tipo de perturbação tem no contexto familiar. Trata-se de um estudo de caso, em que a temática é conhecer o funcionamento familiar e parental numa família com uma criança diagnosticada com PHDA. Assim sendo, os objetivos delineados foram: i) conhecer o funcionamento parental e familiar ao nível das interações e dinâmicas da família, níveis de stress e rede de suporte social; ii) perceber os vínculos estabelecidos entre a criança e os pais; iii) conhecer os problemas de comportamento da criança ao longo do desenvolvimento e na atualidade; iv) analisar as perceções dos pais perante os problemas de comportamento. Para a prossecução do estudo, os instrumentos utilizados foram: a análise documental, o APGAR familiar; a observação naturalista; o Índice de Stress Parental e a entrevista. As conclusões emergentes relacionam-se com a evolução positiva dos comportamentos da criança; a aceitação da problemática por parte do pai, em contraponto com a não-aceitação por parte da mãe; a presença de sentimentos de baixa de autoconfiança/ autoestima; os sentimentos de fraca competência parental; os estilos parentais distintos e a fraca articulação educativa entre progenitores, bem como as diferentes estratégias parentais para o controlo do comportamento da criança.The Hyperactivity Disorder and Attention Deficit (ADHD) is a current theme in the context of the problems of childhood and adolescence development, not only by the increasing number of cases, but also by the fact that the etiology remains unknown. The family is the fundamental core educational accompanying the child's development. In this context, we emphasize parenting practices, interactions and emotional bonds, relevant factors within the family and parental functioning. We present throughout this work several issues related to ADHD, rethinking its conceptualization, differential analysis and the influence that this type of disturbance is in the family context. This is a case study, where the theme is to know the family and parental functioning in families with a child diagnosed with ADHD. Therefore, the outlined objectives were: i) to know the parental family functioning and the level of interaction and family dynamics, stress levels and social support; ii) understand the links established between the child and parents; iii) know the child's behavior problems throughout the development and nowadays; iv) examine parental perceptions before behavioral problems. For further study, the instruments used were: document reviews, the family APGAR; naturalistic observation; Parental Stress Index and the interview. Emerging findings relate to the positive development of children's behavior; acceptance of the problem by the parent as opposed to the non-acceptance by the mother; the presence of feelings of low self-confidence / self-esteem; feelings of poor parenting skills; the different parenting styles and poor educational link between parents and the different parenting strategies for child behavior contro