Non-isothermal Deposition Research Articles

Impact of various aggregation kinetics on thermophoretic velocity of asphaltene deposition.

Asphaltene deposition may pose serious challenges to flow assurance of crude oil in well columns. Different aggregation kinetics would partly be responsible for asphaltene particle growth ending in deposition on the surface of well columns. This work primarily investigates the thermophoretic deposition velocity caused by temperature gradients inside well columns for various asphaltene aggregation kinetics, including crossover behaviour, sedimentation, reaction-limited aggregation (RLA), and diffusion-limited aggregation (DLA). To do so, the experimental observations of size distribution for a live crude oil was performed at 80°C and pressure range of 4500-5500 psia. Moreover, various patterns of different size distributions were gathered from the literature for the sake of comparison. Next, a well column in southern Iran was selected to study the kinetic behaviour of thermophoretic velocity of deposition, with a difference between geothermal and static temperatures of around 5 to 50°C. The non-isothermal deposition velocity was shown to decrease from the top to the bottom of the well column, according to the findings of the study. The results also revealed that the thermophoretic velocity decreases as particle size increases and vice versa. This was confirmed by examining a comparably large range of asphaltene particle sizes, ranging from approximately 100 nm to roughly 9 µm. Practical implications of these findings were also discussed which would provide guidance for mitigation of asphaltene deposition in well columns.

Effect of non-isothermal deposition on surface morphology and microstructure of uniform molten aluminum alloy droplets applied to three-dimensional printing

Non-isothermal deposition of uniform molten droplets as basic building blocks has a great influence on the geometric profile and microstructure of metallic components fabricated by the drop-based three-dimensional (3D) printing technology. In this paper, the thermal and dynamic behaviors of molten aluminum droplets during non-isothermal deposition were studied numerically and experimentally. The result shows that local solidification and interfacial re-melting occur during the initial period of non-isothermal deposition. The re-melting in microseconds depends greatly on the impacting droplet temperature, the deposition surface temperature, and the thermal contact resistance. Further, the coupling action of subsequent solidification and oscillation behaviors of aluminum droplet fixed on the target surface was also investigated. It is interesting to find that the formation and distribution of the solidified surface morphology, such as the typical micron-sized ripples, are significantly affected by layer-by-layer solidification and underdamped oscillation in the remaining molten metal. Based on the above research, a semiquantitative relationship between external morphology and internal microstructure was proposed, which was further certified by investigating the piled vertical columns. The works should be helpful for the process optimization and non-destructive detection of drop-based 3D printing techniques.

Particle deposition with thermal and electrical effects in turbulent flows

Development of relationships for the particle concentration and convection velocity profile has been obtained by the adaptation of the surface renewal model to the particle continuity and momentum equations of the turbulence boundary-layer flow in the presence of thermal field [1]. The predictions obtained on the basis of this model for nonisothermal deposition velocity of particles have been found to be in good agreement with the experimental measurements for fully-developed turbulence tube flow conditions. The aim of this work is to extend the previous model for an applied electric field, with the inclusion of the effect of Coulombic force in addition to the Brownian and turbulent diffusion, the eddy impaction, the turbophoresis, and the thermophoresis. The calculations show an interaction between thermophoresis and turbophoresis in the presence of an applied electric field. The effect of electric force in nonisothermal flows can have a dramatic effect on thermophoretic deposition for τ p + < 0.02 , where turbophoretic effect has ceased. The effect of axial pressure gradient is also included.

Multi-Layer Coating for Optical Mold of Strengthening by Electroplating Ni-W and Electroless Plating Ni-Mo-P by Nonisothermal Method

The development of optical mold coatings has become a key technology in precision optical components in recent years. Researchers are still seeking ideal electroforming materials capable of resisting higher temperature and improve the lifespan of optical mold. Examples of these materials include Ni-W, and Ni-Mo-P alloy plating, among others. However, the literature rarely mentions these alloys as protective coatings. This may be because coating stability, flatness, and strength cannot achieve the desired protective effects. This study develops a combination of two wet electrochemical processes to form a multi-layer coating on optical molds. This coating consists of Ni-W, and Ni-Mo-P alloys. The proposed treatment process attempts to enhance the mechanical strength of the mold and extend its lifespan. We first used electro-deposition to form a thick-film Ni-W coating, and then applied the electroless plating by nonisothermal deposition method (NITD) to create a Ni-Mo-P thin-film and form a multi-layer coating. We also measured the composition, hardness, and elastic modulus of the protective coating as a reference basis for the development of optical molds. The results of this study reveal the appropriate process parameters to provide the multilayer films with a high strength and flat surface. This article can serve as a reference for the development of optical mold coatings.

Fabrication of Co-Mo-P Diffusion Barriers for Copper Interconnect by Non-Isothermal Deposition

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Aluminum Alloys Bipolar Plates Modified by Non-isothermal Deposition and Displacement Deposition Methods

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Defect-Free Copper Filling Using Nonisothermal Electroless Deposition with Fluorocarbon Surfactant

Electroless copper bottom-up filling of patterned substrates using nonisothermal deposition (NITD) with the addition of adequate surfactant was demonstrated. Combining the inhibitive ability of adequate surfactant with the higher driving force of NITD method, superfill of vias or trenches using only one inhibitor in the copper damascene of integrated circuits (ICs) was achieved. We tested several commercial surfactant agents and found that fluorinated alkyl quaternary ammonium iodides (FC) is best compatible to our NITD method. Void-free copper-filled features can be obtained by introducing the surfactant FC into the electroless bath of NITD. Furthermore, using our method, the conductivity of copper film was not negatively affected. We conclude that the surfactant FC combined with NITD method is very promising for the applications in filling trenches and vias with copper films in the IC industry.

Amorphous Ni–Mo–P diffusion barrier deposited by non-isothermal deposition

Ni–Mo–P barrier layers deposited on silicon wafers without Pd activation pretreatment were prepared using the non-isothermal deposition (NITD) method in an acidic electroless bath. The operating conditions for fabricating the Ni–Mo–P barrier layers were presented, and the effect of the pH values on the film composition, electric resistivity and thermal stability have been investigated. The thicknesses of Ni–Mo–P films are around 15–20 nm in acidic bath. Our results indicate increasing amounts of Mo and decreasing amounts of P with increasing pH. The electric resistivity decreased with increasing pH value due to the increase of the Mo content in the Ni–Mo–P film. The amorphous structure was formed at pH 3 and 4, but a quasi-amorphous structure was formed at pH 5. Based on our experimental results, the thermal stability of Ni–Mo–P film prepared at pH 4 remains stable up to 650 °C for 1 h annealing.

Modeling of heat transfer in rotational molding

AbstractRotational molding is a process for manufacturing hollow or open‐sided plastic products using a rotating mold subjected to heating and then cooling. The process is attractive for the production of stress‐free objects at a competitive cost. In this article, a modified model for heat transfer in rotational molding is proposed, which assumes that the heat transfer at the mold‐powder interface is because of convection, whereas the powder particles are heated up by conduction. Heat transfer through the mold–air contact is also included. A source‐based formulation is used for modeling the layer‐by‐layer nonisothermal deposition of plastic. The reduced heat transfer due to warpage is calculated by using a modified heat transfer coefficient. Good overall agreement is found between the cycle times as predicted by the model and the experimental data. The model is then used for calculating the cycle time for particulate composites, based on their effective properties. A reduction in the cycle time is observed in the case of reinforced composites. This is attributed to the increase in thermal conductivity of the particulate composites and the reduced mass fraction of the polymer. Numerical calculations of the cycle time for the glass‐bead reinforced composites are found to be in good agreement with the experimental results. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Electroless copper deposition by non-isothermal deposition technology

In conventional electroless plating of copper, high deposition rate and good bath stability are not easily achieved simultaneously. Some trade-offs must be made. In this study, we provide a novel process called non-isothermal deposition (NITD) method to deposit electroless copper. Our results show this method do provide a promising high deposition rate and the bath life is significantly extended by effectively prohibiting the occurrence of the Cannizzaro reaction within the solution. By this method, the electroless copper can be plated at a temperature as high as 120°C and its deposition rate can be three-fold higher than that gained with the conventional isothermal method. Moreover, a smooth film with the preferred (111) copper crystal plane can be achieved directly by using NITD system without further annealing treatment. It is good for electromigration consideration and it will be effective in lowering the resistivity of the copper deposit.

Electroless deposition of nickel-phosphorous nano-dots for low-temperature crystallization of amorphous silicon

Metal-induced crystallization (MIC) of amorphous silicon (a-Si) is an effective approach for low-temperature formation of polycrystalline silicon thin films. In this study, Ni-P nano-dots were directly deposited on amorphous silicon using a non-isothermal deposition (NITD) method without complicated pretreatment such as surface activation and sensitization. The density of these dots can be controlled by governing the process parameters such as reacting time and substrate temperature. Crystallization of Si was then achieved by annealing at 550 °C. It was found that Si crystallinity increased with Ni deposition time and temperature, and the amorphous Si film was fully crystallized after annealing when Ni-P was deposited at 200 °C for 30 s. We believe this technique can expand the applicability of electroless plating (EP) to metal-induced low-temperature growth of polycrystalline Si films.

A simultaneous annealing effect during high-temperature electroless copper plating using the non-isothermal deposition method

A simultaneous annealing effect on the electroless-plated copper films deposited using the non-isothermal deposition (NITD) method was demonstrated. The Cu films were deposited onto NiMoP/Si substrates and their properties, such as microstructure, resistivity, and crystalline texture, were studied. At a deposition temperature of 400 °C, we found that the resistivity of the as-deposited Cu films was as low as 2.4 μΩ·cm, and X-ray diffraction showed a remarkable (111)/(200) peak ratio of 18.7. It reveals that the NITD system has an excellent capability to deposit and anneal a metal film in one step and does not require any post-annealing process.

Effects of Molybdate Concentration on the Characteristics of Ni – Mo – P Diffusion Barriers Grown by Nonisothermal Electroless Deposition

Ternary Ni-based amorphous films can serve as a barrier layer for Cu interconnects in ultralarge-scale integration (ULSI) applications. In this paper, films deposited on silicon wafers without a complicated pretreatment such as Pd activation were prepared using a nonisothermal deposition (NITD) method. The deposition solutions and operating conditions for preparing the alloys are presented, and the effect of the concentration of added in electrolytes on the deposition rate is investigated. The surface morphology, microstructures, compositions, and electrical resistivity of the deposits are also thoroughly examined. Based on the experimental results, the Ni-based ternary alloys produced by the NITD method contain high levels of both Mo and P, and the properties of films are dependent on the concentration of molybdate in electrolytes. It is concluded that the thin films produced by the proposed approach in this study are promising for the technologies in ULSI.

Ultrathin Ni–Mo–P Diffusion Barriers Deposited Using Nonisothermal Deposition Method in Acid Bath

The performance and thermal stability of the ultrathin nickel-molybdenum-phosphorus (Ni-Mo-P) barrier layer deposited by the nonisothermal deposition method in acid electroless bath have been clearly investigated. The as-deposited Ni-Mo-P film (15 nm) has a low resistivity, contains high amounts of Mo (6.7 atom %) and P (25 atom %), and has an amorphous structure. The barrier capability of this Ni-Mo-P film remains stable up to 650°C for 1 h annealing. This reveals that the resistance of Ni-Mo-P barrier film against Cu diffusion is very prominent, and this method for depositing Ni-Mo-P films is extremely promising for ultralargescale integration application.

Low temperature growth of carbon nanotubes by thermal chemical vapor deposition using non-isothermal deposited Ni–P–Pd as co-catalyst

A novel low temperature growing process of carbon nanotubes (CNTs) on silicon substrate was achieved in this work. The Ni–P catalytic dots were directly deposited on the silicon substrate using an innovative non-isothermal deposition process and then displaced with Pd to form co-catalyst. The substrates and C 2H 2 gas were heated in the reactor to grow the carbon nanotubes. In this study, the temperature at which CNTs can be successfully synthesized is as low as 400 °C with the Ni–P–Pd co-catalyst, while CNTs grew on Ni–P catalyst only at temperatures higher than 600 °C.

Self-assembled nickel–phosphorus micro-dot arrays deposited by non-isothermal deposition method

Micro-dots of nickel–phosphorus alloy (Ni–P) deposited on ITO substrates using non-isothermal deposition method (NITD) were studied. The Ni–P micro-dots can be successfully deposited onto ITO substrate without utilizing complicated pretreatment of Pd/Sn sensitizer, and the number density and mean size of these dots can be controlled by governing the process parameters such as reacting time, substrate temperature, the clearance width and the amount of stabilizer. Adding 100ppm stabilizer (thiourea) to the plating solution help to reduce the size of deposition dots from sub-micro-scale to nano-scale. The capability of controlling the number density of dots and the dot size in NITD method has potential for the application of micro-dots to some industries such as catalysts on CNT growth, low temperature growth of poly-silicon, etc.

Experimental investigation on carbon nanotube grown by thermal chemical vapor deposition using non-isothermal deposited catalysts

The CNTs growth by thermal chemical vapor deposition, incorporating a novel plating technique called non-isothermal deposition (NITD) for preparing catalysts on silicon substrate, was investigated in this study. The aim of this research is to examine the effects of particle size and distribution density of Ni catalysts and Ni-Pd co-catalysts on structure morphology of CNTs. The CNTs were grown by thermal chemical vapor deposition (CVD) using C 2H 2 at various temperatures (ranged from 700 to 900 °C). The size and density of Ni catalysts prepared by NITD process were observed to be increased with the increasing deposition time. The diameter and density of the grown CNTs were noted to be increased with the increasing of the Ni catalyst particle size. The results also proved that using Ni-Pd as a co-catalyst had the effect on reducing the growth temperature for the synthesis of CNTs.

A novel process of electroless Ni–P plating by nonisothermal method

A novel process called nonisothermal method was developed by this work for the electroless Ni–P plating using operating temperature as high as 180 °C and even higher. Results obtained from measuring the open circuit potential (OCP) and the peak current of cyclic voltammetry (CV) indicated that a temperature depended thermal boundary layer with thickness of about 4–10 mm do exist by encompassing the heating substrate in our system. Based on the phenomena of the electrochemistry thermodynamics, the kinetic contour of a nonisothermal deposition (NITD) system could be described since the temperature profile of the thermal layer that governs the deposition reaction and the distance of the heat source with respect to the peak current of CV could be well correlated. The existence of the thermal boundary layer implied that the deposition reactions took place mainly within the thermal boundary layer itself rather than the bulk solution. By this method, the electroless Ni–P plating system even in the absence of the stabilizer can still be stably operated and it could even show two-fold deposition rate in comparison with the conventional method. Deposits performed by the NITD method having the phosphorous content at a level of 10–13% could exhibit a great enhancement on the physicochemical property and the microhardness from 500 up to 612 Hv 0.1 as well.

Pyrolytic Lcvd of Silicon Using A Pulsed Visible Laser - Experiment and Modelling

AbstractMaskless deposition of silicon from silane on Si monocrystalline wafer using copper bromide vapor laser (CBVL) is investigated. Morphology and geometric parameters of the stripes obtained are studied and some conclusions for the process mechanism are made. Applying Kirchoff's transform and Green's function analysis nonlinear heat diffusion problem for different pulse shapes was solved. The influence of pulse shape on the temperature distribution and its time evolution was studied. Nonisothermal and non-stationary deposition kinetic models using the obtained results were developed.