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The development of glass substrates for use as an alternative to printed circuit boards (PCBs) attracts significant industrial attention, because of the potential for low cost but high performance interconnects and optical connection. Electroless plating is currently used to deposit conductive tracks on glass substrates and the quality of copper / glass adhesion is a key functional issue. Without adequate adhesive strength the copper plating will prematurely fail. Existing studies have covered the relationship between surface roughness and adhesion performance, but few of them have considered the detail of surface topography in any depth. This research is specifically considering the mechanical contribution of the glass surface texture to the copper / glass adhesive bond, and attempting to isolate new ISO 25178 areal surface texture parameters that can describe these surfaces. Excimer laser machining has been developed and used to create a range of micro pattern structured surfaces on CMG glass substrates. Excimer mask dimensions and laser operation parameters have been varied and optimized according to surface topography and adhesion performance of the samples. Non-contact surface measurement equipment (Zygo NewView 5000 coherence scanning interferometry) has been utilized to measure and parameterize (ISO 25178) the surface texture of the glass substrates before electroless copper metallization. Copper adhesion quality has been tested using quantitative scratch testing techniques, providing an identification of the critical load of failure for different plated substrates. This research is establishing the statistical quality of correlation between the critical load values and the associated areal parameters. In this thesis, the optimal laser processing parameter settings for CMG glass substrate machining and the topographic images of structured surfaces for achieving strong copper / glass plating adhesion are identified. The experimental relationships between critical load and areal surface parameters, as well as the discussions of a theoretical approach are presented. It is more significant to consider Sq, Sdq, Sdr, Sxp, Vv, Vmc and Vvc to describe glass substrate surface topography and the recommended data value ranges for each parameter have been identified to predict copper / plating adhesion performance.

Ultrasonic Consolidation (UC) is a solid state additive manufacturing process which fabricates three-dimensional objects by ultrasonically joining metal foils together, layer-bylayer, to form a solid part. A wide range of materials can be used to fabricate parts by UC and products with complex internal geometry can be generated by shaping the crosssection throughout the build using Computer Numerically Controlled (CNC) milling. As a result of its ability to embed various secondary materials and fibres in metal matrices, UC has emerged as a potential method of fabricating multi-functional materials and structures.

A survey of the literature of grinding and surface texture shows the influence of dressing and wear on surfaces involved in the process and the advantages of stylus profilometry for data collection from both grinding wheels and ground surfaces. Statistical analysis is favoured for surface profile characterization and, of the various parameters used, power spectral density alone offers some prospect of effective comparison between these surfaces. Work on grinding with single crystals of natural corundum was eventually discontinued in favour of experiments with conventional bonded grinding wheels subjected to a dressing operation and some wear in grinding steel surfaces. Statistical parameters representing the surfaces are computed using data obtained from profilograms. Results in terms of power spectral density are presented showing progressive improvement following upon developments in apparatus and methods which facilitated the use of larger surface profile samples. Transfer functions are used to relate power spectra representing corresponding pairs of surfaces. The significance of power spectral density applied to surface profile characterization is discussed and, in this context, it is suggested that these should be described as variance spectra. Attention is drawn to certain disadvantages of variance spectra applied to grinding wheel and ground surface profiles. Methods designed to improve presentation of variance spectra lead to development of a proposed new and more suitable spectrum in which density of standard deviation of surface profile ordinates with respect to frequency is plotted against frequency. Transfer functions calculated from related pairs of these standard deviation spectra show a strong linear correlation with frequency and offer prospects of convenient comparison between the profiles of the various surfaces involved in grinding.

The objective of this research was to understand the evolution of surface texture under boundary/mixed lubrication (BL). Significant material/energy losses occur during BL because of direct contact between the two surfaces. Traditionally, tribofilms have been studied extensively for BL while textures have been used as a static engineering design parameter to enhance lubricant film properties. However, texture is dynamic at the tribological mating interface, where both physical and chemical interactions are continuously modulated. The evolution and the interplay between the tribofilm and texture is least studied in the literature, which is the focus of this research. MoS2-based lubricants, known for their excellent anti-friction and anti-wear performance [1]–[3], were used during the experiments. The experiments were divided into two parts; 1) polished steel discs were used to study directed organization/re-organization of surface asperities in correlation with tribofilm; 2) textured discs were used to study the effect of artificial texture on manipulation of tribofilm properties. Three stages of lubrication evolution, namely break-in, development, and steady-state, were discovered and studied experimentally. Surface texture was characterized using laser scanning microscope. Tribofilm morphology and chemistry was studied using scanning and transmission electron microscopy and Raman spectroscopy. The results showed that the surface roughness increases during break-in period and then stabilizes. Addition of directional texture results in early onset and stabilization of tribo-chemical reactions. Raman spectra confirmed presence of MoS2, FeS2, Fe2O3, and molybdate compounds, consistent with previous studies. [3] Cross-sectional TEM images revealed presence of stored lubricant in valleys while delivering lamellar tribo-layer on asperities. From the results, the following lubrication mechanism was discussed. Initially, during the break-in period, contact between mating surfaces results in re-organization/re-alignment surface asperities under the applied load and directional motion. Creation of fresh asperities in the presence of lubricant along with energy dissipation is responsible for the onset of tribo-chemical reactions. Subsequently, during the development stage, progressing reactions between surface asperities and lubricant lead to formation and stabilization of tribofilm. Eventually, in the steady-state, stabilized texture and tribofilm results in stable lubrication response. The findings of this research will benefit heavy-duty industrial applications involving low-speed, high-load conditions.

Synthetic scaffolds are widely used as implants to repair bone fracture. Without a proper design, scaffolds could pose significant health risks to the patient and fail to heal the bone properly. A good synthetic scaffold needs to have high porosity and large pore size to allow new bone cells to form on it. However, a scaffold with higher porosity and larger pore size tends to have reduced mechanical strength. Thus, it is important to find a structural design which allows the implant to have a high porosity and large pore size while retaining high strength. In this research, a 3D-printable bio-inspired structure based on the unit cell of hydroxyapatite (HAp), along with several other common scaffold structures, were designed and tested using a multiscale approach. Those structures are tested under different loading conditions to find the stress levels. HAp material properties are extracted from the density functional theory calculations, and the effect of porosity on the material properties are modeled based on empirical relations by utilizing the density as the scaling factor. The results show that the HAp-inspired scaffold could have up to 70% lower stress level when compared to other common scaffold designs，such as round or square pores scaffolds, under the same loading condition. Due to substitutions during aging, the scaffolds made of apatite can be significantly different from stoichiometric HAp. Hence, this study is also extended to test the HAp-inspired scaffold with varying anionic and cationic substitutions, including Mg2+, Zn2+, and CO32-. Furthermore, the surface texture of synthetic scaffolds has also become an important research subject in the last decade. Studies have found that surface texture can alter surface properties, such as cell adhesion, protein adsorption, and coefficient of friction, of a biomaterial. In this study, two of very promising 3D-printable bio-inspired surface textures are studied for their stress reaction under a loading condition. Some advice that could lead to a structurally stronger surface texture design is concluded. This study will provide an insight into a better scaffold design based on bio-inspired structures and the effects of substitutions on HAp scaffolds.

Particle morphology outlines the general analytical method used to describe soil particles’ structure and shape. The characteristics defining this term include sphericity, roundness, and surface texture. Particle morphology has a significant influence on sand behavior and consequently affects dilatancy and friction. Understanding the relationship between shear strength parameters and particle morphology answers fundamental questions about the mechanics of granular materials in general and has the potential to enhance the development of advanced constitutive models that describe granular materials’ behavior. Many researchers have reported measurements for sphericity, roundness, and surface texture using both two-dimensional (2D) and three-dimensional (3D) images to analyze the effects on granular materials’ friction and dilatancy angles. This thesis investigates the influence of morphology measurements from 3D images on friction and dilatancy of three types of sands (#1 Dry Glass, GS#40 Columbia, and F-35 Ottawa Sand) and on glass beads. A series of direct shear experiments were conducted at various normal stresses and densities to achieve this goal. Experimental measurements of friction and dilatancy angles were compared to findings in a previous study. A stepwise regression analysis was performed to develop statistical models predicting friction and dilatancy using the specimen’s relative density, normal stress, and particle morphology as input parameters. This thesis discusses how these explanatory variables affect the model and compares the experimental results with the predicted values. A reasonable agreement is found between the model’s predictions and the experimental results. The development of simple statistical models capable of accurately predicting friction and dilatancy values has a major impact on many field applications (e.g., processing granular materials for industrial and engineering purposes, foundation design, landslides, agricultural and pharmaceutical products, and future research on granular materials’ behavior). This study contributes to further advancements in theories predicting granular materials’ behavior and provides experimental evidence to support improvements of constitutive models that describe the behavior of sands.

The characteristics of fine aggregates, such as shape, angularity, and surface texture, have been shown to influence the performance of concrete and asphalt mixtures and to play an important role in obtaining valuable properties of early age concrete such as workability, and compatibility. However, the measurement of fine aggregate characteristics is not easy. In the present study, 26 fine aggregates, covering a wide spectrum of mineralogy, were examined using direct and indirect test methods in order to evaluate the shape, angularity, and surface texture, as well as to analyze the gradation. The direct test methods, such as AIMS and Camsizer, which provide a digital image of the aggregates proved to be the best. However, the cost of such systems can limit the use of digital imagining systems in practice. The indirect test methods which provide an estimate of aggregate surface characteristics, such as uncompacted void test, mortar flow test, compressive strength test, and flakiness test gave variable results. The uncompacted void test (Method A) was shown to be the most accurate indirect test method. The Camsizer and the sieve analysis test produced identical gradation analysis results when an adequate sample was used. General correlations were developed between the direct and indirect test methods. The non-approved fine aggregates on the TxDOT’s list were analyzed and compared to those of the approved fine aggregates to see whether they could be successfully used. It was found that both LS-5 and LS-8 had good results—even better than the results of some of the approved fine aggregates. Thus, they could be successfully used.