Methods for reversible surface modification

Abstract

Method for the reversible surface modification of metal and glass surfaces incompatible with infrared optical measurements for temporary matting, sealing, and preservation for optical measurements using fringe projection, laser, or thermographic methods, wherein a means is first applied to the surface of the object under investigation to produce at least one thin layer with uniform spectral reflectance and scattering properties, enabling optical measurement, wherein an optical measurement is then carried out using fringe projection, laser, or thermographic methods, and wherein the means used to produce the at least one layer, due to its volatility, removes itself automatically and without residue after application by sublimating the reflectance and scattering layers under normal atmosphere after a residence time of a few minutes to several hours.characterized in that an agent is used which has the hydrocarbon adamantane as an essential component, wherein the adamantane is used as a component of a solution consisting of 1 to 15% adamantane and 99 to 85% medium- or low-boiling light naphtha or cyclohexane or where the adamantane is used as a component of a solution consisting of 1 to 15 wt% adamantane and 99 to 85 wt% 2-methylbutane or wherein the adamantane is used in a saturated solution tempered at 50°C as a component of a solution consisting of 5% adamantane and 80% ethanol and 15% medium-boiling light naphtha or wherein the adamantane is used as a component of a supersaturated solution consisting of 15 to 30 wt% adamantane and 85 to 70 wt% ethanol or naphtha or cyclohexane or wherein the adamantane is used in a saturated solution tempered at 50°C as a component of a solution consisting of 15 wt% to 20 wt% adamantane and 85 wt% to 80 wt% medium-boiling light naphtha or cyclohexane.

Description

[0001] The invention relates to a method for the reversible surface modification of metal and glass surfaces incompatible with infrared optical measurements for temporary matting, sealing, and preservation for optical measurements using fringe projection, laser, or thermographic methods, wherein a means is first applied to the surface of the object to be measured to produce at least one thin layer with uniform spectral reflectance and scattering properties, which enables optical measurement, wherein an optical measurement is then carried out using fringe projection, laser, or thermographic methods, and wherein the means used to produce the at least one layer removes itself automatically and without residue after application due to its volatility.by the reflection and scattering layers sublimating under normal atmosphere after a residence time of a few minutes to several hours.

[0002] The quality of photometric and radiometric measurements is largely determined by the reflection, scattering, and emission properties of the surfaces being measured. For light-based profile measurement methods, diffuse light reflection on the outer surfaces of the object being measured is often desirable. For non-contact temperature measurements with pyrometers and thermographic cameras, the temperature-dependent spectral emissivity of the object's material must be known, and the detected area must exhibit the highest possible emissivity for the infrared measurement radiation.

[0003] Many currently available photometric profile measuring devices in the visible spectral range reach their limits when measuring completely transparent, translucent, absorbing, reflective, or glossy surfaces. Additional measures to adapt the lighting, sensor, and optical imaging to the object properties are often ineffective for achieving optimal imaging in such cases. Measurement and positioning strategies to avoid measurement errors or reduce artifacts often require not only expert knowledge but also significant methodological, temporal, and technical resources.

[0004] To prepare object surfaces that are difficult or impossible to measure for optical 3D scanning, whitening agents based on inorganic pigments (for example, titanium dioxide, chalk, or barium sulfate) are typically used. The use of non-volatile anti-reflective agents from product photography, based on stable hydrocarbons, is also common.

[0005] When surfaces are pretreated with white pigments, the sprayed powder coating lies loosely on the surface and can be easily damaged by touch. Due to the relatively thick white layers with their high granularity, significant measurement errors occur when using optical micromeasurement techniques such as confocal, triangulation-based, autofocusing, and focus variation-based methods.

[0006] Permanent dyes are also used in surface inspection of welds and safety components to make wrinkles, pores, and cracks more visible. Visualizing these defects is based on the principle of dye penetration.

[0007] In non-contact temperature measurements using thermographic methods, durable paints and pigments with high spectral emissivity are applied to smooth metal surfaces to reliably detect IR radiation and to avoid directional reflections and large emissivity variations.

[0008] These methods of surface preparation, aimed at matting surfaces or highlighting surface defects through contrast enhancement, are only suitable for objects and measuring rooms where cleanliness is not a primary concern. The durable reflective coatings deposited on valuable objects must subsequently be removed. When coating extensive surfaces, such cleaning is complex and not always satisfactory, as material residues may remain. For sensitive and delicate objects (e.g., precision engineering components with microcavities or open-pore structures), the application of such long-term stable agents inevitably leads to irreversible surface contamination or abrasion.

[0009] Therefore, the aim is to apply thin, optically effective, non-contact layers with uniform diffuse reflection in all directions and across the spectrum of the measuring light or radiation to optically incompatible object surfaces. These layers dissolve spontaneously and completely after a certain period without any additional steps, so that the object is restored to its original condition. Suitable agents for this purpose are those that are volatile even at room temperature or slightly higher. Consequently, due to their volatility, such agents remove themselves completely within a relatively short time, thus eliminating the need for layer removal.

[0010] A corresponding technical solution is known from DE 44 02 074 C2. In this process, a liquid preparation is first applied to the surface of a measurement object whose reflective properties are to be modified, either by spraying or brushing. Immediately after application, a solvent contained in the liquid preparation evaporates. This leaves only a dissolved substance on the object's surface. This substance, in combination with a solvent such as ethanol, forms a white, opaque surface coating based on physical principles. This coating exhibits reflective properties and is therefore used as a measuring layer. The substance component forming this layer is a compound that sublimates even at room temperature. Consequently, this layer also evaporates spontaneously after a certain period of time on the object.However, the use of conventional solvents during processing does not preclude a reaction with the object being measured.

[0011] Furthermore, it is known to use volatile film formers such as cyclododecane (CCD) and camphene for applications in the field of restoration and conservation for the mechanical stabilization and sealing of objects or surfaces. EP 2 829 328 A1 relates to an application device for applying a sublimable and condensable compound to component surfaces. Cyclododecane is preferably used, which is advantageously employed for the restoration of paper documents.

[0012] Although substances already known from restoration and conservation, such as cyclododecane, camphene, and menthol, are generally suitable for metrological applications, there is a need for further development in the use of other substances to achieve even better measurement results for specific applications. For example, applying cyclododecane from spray cans is only conditionally suitable for creating temporary measurement layers because dosing is difficult and strong crystal formation occurs during application. This results in relatively coarse layers with irregular thickness, which are unsuitable for high-resolution optical scans.

[0013] Furthermore, there is a great need to use reversible coating technology with volatile solids for optical micro- and nanomeasurement technology, optical surface testing and radiation-based temperature measurement.

[0014] German patent DE 27 56 953 A1 describes a sublimating mass containing adamantane. This sublimating mass is used to form a molded body as a carrier for perfume oils, deodorants, and the like.

[0015] JP S54-147 144 A concerns a sublimable rust inhibitor which contains, among other things, adamantane and solvents.

[0016] US 2009 / 0220602A1 describes a method for delivering a biologically active agent (animal drug) to an animal. This involves administering a composition comprising at least one sublimable matrix material and the biologically active agent to the animal. Adamantane is used as one of the matrix materials.

[0017] The object of the invention is to propose a method for applying thin, optically effective layers with uniform diffuse reflection or high emission to measurement objects, whereby the agents, due to their volatility, should be removable without residue in a relatively short time. The aim is thus to utilize chemically inert hydrocarbons with a relatively high optical refractive index, which transition from the solid to the gaseous state under normal conditions or with a slight increase in temperature. This should, in particular, create new possibilities for the gentle matting, sealing, and preservation of functional surfaces on measurement objects.

[0018] This problem is solved according to the invention with the technical features according to claim 1.

[0019] The basic approach therefore involves applying adamantane to the surface for the temporary matting, sealing and preservation of surfaces of preferably geometrically complex spatial objects in the form of a reversible surface modification.

[0020] This white, waxy, non-toxic, and fluorescent solid consists of four cyclohexane rings, which are stable and inert, ensuring good film formation properties. Due to its inherent refractive index, the resulting layers exhibit high opacity, reflectivity, and scattering of light. Because of their excellent thermal conductivity and emissivity, volatile diamondoids, such as adamantane, are well-suited as temporary coatings for infrared optical measurements on incompatible metal and glass surfaces.

[0021] The applied adamantane layers evaporate relatively quickly due to the vapor pressure increasing with temperature. However, this period is process-reliable and longer than the time required for optical measurement methods. This allows for faster, targeted stripping of pretreated surfaces (through ventilation, temperature increase, negative pressure, etc.), especially on large components. This is particularly advantageous for in-process measurements (e.g., inline testing).

[0022] Due to the outstanding chemical and physical properties of adamantan, there are numerous possibilities for the concrete implementation of the solution approach according to the invention.

[0023] Thus, vapor deposition (also known for alternative agents) can be achieved under atmospheric pressure and even at moderate temperatures, which is due to a significant increase in the vapor pressure of adamantane with rising temperatures; see Florian, W. “Measurement of the vapor pressure of adamantane”, Zeitschrift für Physikalische Chemie, Vol. 61 (1968), pp. 319-321.

[0024] Furthermore, processing and application from the solution are possible. This processing can be carried out both cold and heated.

[0025] In summary, the solution approach according to the invention provides alternative means and coating processes that enable optical measurement on object surfaces for a specific duration. Depending on the coating material, the thickness and density of the layer, and the ambient conditions, the dwell time ranges from a few minutes to several hours. After measurement, the reflective and scattering layers sublimate under normal atmospheric conditions without leaving any residue on the surfaces. Final cleaning is not required. The organic mixtures are chemically neutral and harmless to health. In contrast to the white pigments used previously, light reflection is generated by the type, size, and arrangement of short-lived crystals.The resulting volatile optically effective coatings are particularly advantageous for optical measurements using fringe projection and laser methods as well as thermographic methods.

[0026] The following are examples of possible embodiments of the invention: Vapor deposition can be achieved by heating solid adamantane to temperatures above 100°C, causing a thin white precipitate to form on the substrate within a few seconds. Under normal conditions, the visible crystal layers remain in place for several hours.

[0027] For cold processing from a solution, it is suggested that 1 to 10% adamantane be dissolved in 90 to 99% medium- or low-boiling naphtha or cyclohexane. This results in faint white layers on the respective surface after dipping and spraying.

[0028] For a composition of adamantane and a volatile solvent, it is proposed that 1 to 15 wt% adamantane and 99 to 85 wt% 2-methylbutane be mixed and brought to a saturated solution.

[0029] For processing a highly supersaturated solution of adamantane and a polar or nonpolar solvent, it is proposed that the adamantane is first dispersed into very fine nanometer-sized particles and then mixed with ethanol, 2-methylbutane, or naphtha to create a liquid mixture. Various formulations are possible; preferred compositions consist of 15 to 30 wt% adamantane and 85 to 70 wt% solvent. Application of coating methods such as dipping or spraying with this solution results in a white, chalk-like layer, with the adamantane being deposited uniformly and completely on the surface.

[0030] For heated processing at a temperature of at least 50°C, it is proposed that the saturated solution consist of 15% to 20% adamantane and 85% to 80% medium-boiling light naphtha or alcohol. This results in largely amorphous white layers without the formation of large crystal structures.

[0031] As a further formulation of a saturated solution at 50°C, 5% adamantane, 80% ethanol, and 15% medium-boiling light naphtha are proposed. This results in a mixture that is liquid and usable even at room temperature.

[0032] The aforementioned processes result in mattifying white coatings that can achieve satisfactory diffuse reflection or radiation emission on reflective, absorbing and transparent surfaces for optical measurement technology.

Claims

[1] Method for the reversible surface modification of metal and glass surfaces incompatible with infrared optical measurements for temporary matting, sealing and preservation for optical measurements using fringe projection or laser methods or thermographic methods, wherein a means is first applied to the surface of the object to be measured to produce at least one thin layer with uniform spectral reflectance and scattering power, which enables optical measurement capability, wherein an optical measurement is then carried out using fringe projection or laser methods or thermographic methods and wherein the means used to produce the at least one layer removes itself automatically and without residue after application due to its volatility, by the reflection and scattering layers sublimating under normal atmosphere after a residence time of a few minutes to several hours,characterized by that a substance is used which contains the hydrocarbon adamantane as a key component, wherein the adamantane is used as a component of a solution consisting of 1 to 15% adamantane and 99 to 85% medium- or low-boiling light naphtha or cyclohexane or where the adamantane is used as a component of a solution consisting of 1 to 15 wt% adamantane and 99 to 85 wt% 2-methylbutane or wherein the adamantane is used in a saturated solution tempered at 50°C as a component of a solution consisting of 5% adamantane and 80% ethanol and 15% medium-boiling light naphtha or wherein the adamantane is used as a component of a supersaturated solution consisting of 15 to 30 wt% adamantane and 85 to 70 wt% ethanol or naphtha or cyclohexane or wherein the adamantane is used in a saturated solution tempered at 50°C as a component of a solution consisting of 15 wt% to 20 wt% adamantane and 85 wt% to 80 wt% medium-boiling light naphtha or cyclohexane.